Dr. Ian Howard

Advanced Materials and Optical Spectroscopy

Engesserstrasse 13, Geb. 30.34
76131 Karlsruhe

Research Interests

My research uses spectroscopy to explore the fundamental optoelectronic properties of solution-processable semiconductors. I am currently especially interested in organic semiconductors and metal organic frameworks. The ultimate goal of this research is to understand how energy flow is controlled at the nanoscale in these materials, and to use this knowledge to help design better materials for low-cost solar energy conversion.

For a complete list of publications please see my google citations, or ResearcherID profile.

Short CV

2014-present	Group leader Advanced Materials and Optical Spectroscopy at KIT.
2009-2014	Alexander von Humboldt and Max Planck Fellow at the Max Planck Institute for Polymer Research in Mainz.
2005-2009	Ph.D in Physics from King's Collage, University of Cambridge. Performed in the Optoelectronics Group at the Cavendish Labratory unter the advisement of Prof. Neil Greenham. Title "Loss Mechanisms in High Open-Circuit Voltage Organic Sollar Cells".
2005	Undergraduate thesis with Prof. Sargent on solution-processed nanocrystal-baseed detectorts now commercialized through the spin-off company Invisage Inc.
2000-2005	Undergraduate degree in Engineering Science at the University of Toronto.

Publikationen

2024

Enhanced Predictability of Urea Crystallization by an Optimized Laser Repetition Rate
Geiger, L.; Howard, I.; MacKinnon, N.; Forbes, A.; Korvink, J. G.
2024. Crystal Growth & Design. doi:10.1021/acs.cgd.3c01210

Tb and Eu in MOF‐76: Elucidating the Mechanisms Responsible for the Divergent Excellent and Poor Photoluminescence Quantum Yields
Meng, D.; Zhao, T.; Busko, D.; Cosgun Ergene, A.; Richards, B. S.; Howard, I. A.
2024. Advanced Optical Materials. doi:10.1002/adom.202300867

2023

High Quantum Yield Shortwave Infrared Luminescent Tracers for Improved Sorting of Plastic Waste
Rajagopalan, K.; Madirov, E.; Busko, D.; Howard, I. A.; Richards, B. S.; Swart, H. C.; Turshatov, A.
2023. ACS Applied Materials & Interfaces, 15 (37), 43985 – 43993. doi:10.1021/acsami.3c07387

Tunable J-type aggregation of silicon phthalocyanines in a surface-anchored metal–organic framework thin film
Chen, H.; Martín-Gomis, L.; Xu, Z.; Fischer, J. C.; Howard, I. A.; Herrero, D.; Sobrino-Bastán, V.; Sastre-Santos, Á.; Haldar, R.; Wöll, C.
2023. Physical Chemistry Chemical Physics, 25 (29), 19626–19632. doi:10.1039/D3CP01865B

Solar-pumped fiber laser using a solid-state luminescent solar collector
Endo, M.; Yamamoto, K.; Dottermusch, S.; Howard, I. A.; Richards, B. S.; Tomizawa, R.; Masuda, T.
2023. Optics Express, 31 (16), 26040–26053. doi:10.1364/OE.496268

Absolute quantum yield for understanding upconversion and downshift luminescence in PbF $_{2}$ :Er $^{3 +}$ ,Yb $^{3 +}$ crystals
Madirov, E.; Busko, D.; Howard, I. A.; Richards, B. S.; Turshatov, A.
2023. Physical Chemistry Chemical Physics, 25 (17), 11986–11997. doi:10.1039/D3CP00936J

Optimization of laser-induced OH Radical Generation in Water
Geiger, L. M.; Jouda, M.; Länge, K.; Rapp, M.; Voigt, A.; Howard, I.; MacKinnon, N.; Korvink, J.
2023, April 18. Experimental Nuclear Magnetic Resonance Conference (ENC 2023), Pacific Grove, CA, USA, 16.–21. April 2023

Enhancement of Amplified Spontaneous Emission by Electric Field in CsPbBr $_{3}$ Perovskites
Li, Y.; Hu, H.; Farag, A.; Feeney, T.; Allegro, I.; Lemmer, U.; Paetzold, U. W.; Howard, I. A.
2023. Nano Letters, 23 (5), 1637–1644. doi:10.1021/acs.nanolett.2c02944

Intensity Dependent Photoluminescence Imaging for In‐Line Quality Control of Perovskite Thin Film Processing
Hacene, B.; Laufer, F.; Ternes, S.; Farag, A.; Pappenberger, R.; Fassl, P.; Moghadamzadeh, S.; Nejand, B. A.; Feeney, T.; Howard, I.; Paetzold, U. W.
2023. Advanced Materials Technologies. doi:10.1002/admt.202301279

Luminescent solar concentrators for building integrated photovoltaics: opportunities and challenges
Richards, B. S.; Howard, I. A.
2023. Energy & Environmental Science, 16 (8), 3214–3239. doi:10.1039/d3ee00331k

GIWAXS Characterization of Metal–Organic Framework Thin Films and Heterostructures: Quantifying Structure and Orientation
Fischer, J. C.; Li, C.; Hamer, S.; Heinke, L.; Herges, R.; Richards, B. S.; Howard, I. A.
2023. Advanced Materials Interfaces, 10 (11), Art.-Nr.: 2202259. doi:10.1002/admi.202202259

Smartphone Authentication of Unclonable Anticounterfeiting Labels based on a Microlens Array atop a Microphosphor‐Doped Layer
Kumar, V.; Gota, F.; Neyret, J.; Katumo, N.; Chauhan, A.; Dottermusch, S.; Richards, B. S.; Howard, I. A.
2023. Advanced Materials Technologies, 8 (6), Art.-Nr.: 2201311. doi:10.1002/admt.202201311

Comparison of Quantum Yield of Upconversion Nanocrystals Determined by Absolute and Relative Methods
Madirov, E.; Busko, D.; Cardona, F. A.; Hudry, D.; Kuznetsov, S. V.; Konyushkin, V. A.; Nakladov, A. N.; Alexandrov, A. A.; Howard, I. A.; Richards, B. S.; Turshatov, A.
2023. Advanced Photonics Research, 4 (2), Art.-Nr.: 2200187. doi:10.1002/adpr.202200187

2022

Expanding the Angle of Incidence Tolerance of Unclonable Anticounterfeiting Labels Based on Microlens Arrays and Luminescent Microparticles
Kumar, V.; Dottermusch, S.; Chauhan, A.; Richards, B. S.; Howard, I. A.
2022. Advanced Photonics Research, 3 (6), Art.-Nr.: 2100202. doi:10.1002/adpr.202100202

Correlative In Situ Multichannel Imaging for Large-Area Monitoring of Morphology Formation in Solution-Processed Perovskite Layers
Ternes, S.; Laufer, F.; Scharfer, P.; Schabel, W.; Richards, B. S.; Howard, I. A.; Paetzold, U. W.
2022. Solar RRL, 6 (3), Art.-Nr. 2100353. doi:10.1002/solr.202100353

Limitation of room temperature phosphorescence efficiency in metal organic frameworks due to triplet-triplet annihilation
Zhao, T.; Busko, D.; Richards, B. S.; Howard, I. A.
2022. Frontiers in Chemistry, 10, Art.-Nr.: 1010857. doi:10.3389/fchem.2022.1010857

Charge Carrier and Exciton Dynamics in Perovskites Revealed by Time‐Integrated Photoluminescence after Double‐Pulse Excitation
Kaiser, M.; Li, Y.; Gharibzadeh, S.; Richards, B. S.; Paetzold, U. W.; Howard, I. A.
2022. Advanced Materials Technologies, 7 (11), Art.Nr.: 2200152. doi:10.1002/admt.202200152

Lasing from Laminated Quasi‐2D/3D Perovskite Planar Heterostructures
Li, Y.; Roger, J.; Allegro, I.; Fischer, J. C.; Jin, Q.; Lemmer, U.; Howard, I. A.; Paetzold, U. W.
2022. Advanced Functional Materials, 32 (27), Artkl.Nr.: 2200772. doi:10.1002/adfm.202200772

Unclonable Anti-Counterfeiting Labels Based on Microlens Arrays and Luminescent Microparticles
Kumar, V.; Dottermusch, S.; Katumo, N.; Chauhan, A.; Richards, B. S.; Howard, I. A.
2022. Advanced Optical Materials, 10 (9), Art.-Nr.: 2102402. doi:10.1002/adom.202102402

Dual-color dynamic anti-counterfeiting labels with persistent emission after visible excitation allowing smartphone authentication
Katumo, N.; Li, K.; Richards, B. S.; Howard, I. A.
2022. Scientific reports, 12 (1), Art.Nr.: 2100. doi:10.1038/s41598-022-05885-6

BODIPY–pyrene donor–acceptor sensitizers for triplet–triplet annihilation upconversion: the impact of the BODIPY-core on upconversion efficiency
Kiseleva, N.; Filatov, M. A.; Fischer, J. C.; Kaiser, M.; Jakoby, M.; Busko, D.; Howard, I. A.; Richards, B. S.; Turshatov, A.
2022. Physical chemistry, chemical physics, 24 (6), 3568–3578. doi:10.1039/d1cp05382e

Light Management for Enhancing Optical Gain in a Solar‐Pumped Fiber Laser Employing a Solid‐State Luminescent Solar Concentrator
Masuda, T.; Aoyagi, K.; Dottermusch, S.; Howard, I. A.; Richards, B. S.; Endo, M.
2022. Advanced photonics research, 3 (2), Art.Nr.: 2100214. doi:10.1002/adpr.202100214

2021

Experimental validation of a modeling framework for upconversion enhancement in 1D-photonic crystals
Hofmann, C. L. M.; Fischer, S.; Eriksen, E. H.; Bläsi, B.; Reitz, C.; Yazicioglu, D.; Howard, I. A.; Richards, B. S.; Goldschmidt, J. C.
2021. Nature Communications, 12 (1), Aricle no: 104. doi:10.1038/s41467-020-20305-x

Interface Pattern Engineering in Core-Shell Upconverting Nanocrystals: Shedding Light on Critical Parameters and Consequences for the Photoluminescence Properties
Hudry, D.; De Backer, A.; Popescu, R.; Busko, D.; Howard, I. A.; Bals, S.; Zhang, Y.; Pedrazo-Tardajos, A.; Van Aert, S.; Gerthsen, D.; Altantzis, T.; Richards, B. S.
2021. Small, 17 (47), Art.-Nr. 2104441. doi:10.1002/smll.202104441

The potential of SWCNTs to extend the IR-absorption of silicon solar cells
Wieland, L.; Rust, C.; Li, H.; Jakoby, M.; Howard, I.; Li, F.; Shi, J.; Chen, J.; Flavel, B. S.
2021. Carbon, 184, 828–835. doi:10.1016/j.carbon.2021.08.080

In situ reflectance- photoluminescence imaging on solution-processed perovskite thin-films
Ternes, S.; Laufer, F.; Scharfer, P.; Schabel, W.; Richards, B. S.; Howard, I. A.; Paetzold, U.
2021. 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC), 1472–1475, Institute of Electrical and Electronics Engineers (IEEE). doi:10.1109/PVSC43889.2021.9518569

Rare-earth coordination polymers with multimodal luminescence on the nano-, micro-, and milli-second time scales
Jakoby, M.; Beil, C.; Nazari, P.; Richards, B. S.; Seitz, M.; Turshatov, A.; Howard, I. A.
2021. iScience, 24 (3), Art. Nr.: 102207. doi:10.1016/j.isci.2021.102207

Ratiometric Luminescent Thermometry with Excellent Sensitivity over a Broad Temperature Range Utilizing Thermally‐Assisted and Multiphoton Upconversion in Triply‐Doped La₂O₃:Yb³⁺/Er³⁺/Nd³⁺
Gao, G.; Busko, D.; Katumo, N.; Joseph, R.; Madirov, E.; Turshatov, A.; Howard, I. A.; Richards, B. S.
2021. Advanced optical materials, 9 (5), Art.-Nr.: 2001901. doi:10.1002/adom.202001901

Method for accurate experimental determination of singlet and triplet exciton diffusion between thermally activated delayed fluorescence molecules
Jakoby, M.; Heidrich, S.; Graf von Reventlow, L.; Degitz, C.; Suresh, S. M.; Zysman-Colman, E.; Wenzel, W.; Richards, B. S.; Howard, I. A.
2021. Chemical science, 12 (3), 1121–1125. doi:10.1039/d0sc05190j

Interpreting the Time-Resolved Photoluminescence of Quasi-2D Perovskites
Kaiser, M.; Li, Y.; Allegro, I.; Richards, B. S.; Paetzold, U. W.; Howard, I. A.
2021. Advanced Materials Interfaces, 8 (24), Art.-Nr.: 2101326. doi:10.1002/admi.202101326

Photon Upconversion for Photovoltaics and Photocatalysis: A Critical Review – Focus Review
Richards, B. S.; Hudry, D.; Busko, D.; Turshatov, A.; Howard, I. A.
2021. Chemical reviews, 121 (15), 9165–9195. doi:10.1021/acs.chemrev.1c00034

Exciton versus free carrier emission: Implications for photoluminescence efficiency and amplified spontaneous emission thresholds in quasi-2D and 3D perovskites
Li, Y.; Allegro, I.; Kaiser, M.; Malla, A. J.; Richards, B. S.; Lemmer, U.; Paetzold, U. W.; Howard, I. A.
2021. Materials Today, 49, 35–47. doi:10.1016/j.mattod.2021.05.002

Anticounterfeiting Labels with Smartphone‐Readable Dynamic Luminescent Patterns Based on Tailored Persistent Lifetimes in Gd $_{2}$ O $_{2}$ S:Eu $^{3 +}$ /Ti $^{4 +}$
Katumo, N.; Ruiz-Preciado, L. A.; Kumar, V.; Hernandez-Sosa, G.; Richards, B. S.; Howard, I. A.
2021. Advanced materials technologies, 6 (7), Art.-Nr.: 2100047. doi:10.1002/admt.202100047

Solar Pumping of Fiber Lasers with Solid-State Luminescent Concentrators: Design Optimization by Ray Tracing
Dottermusch, S.; Masuda, T.; Endo, M.; Richards, B. S.; Howard, I. A.
2021. Advanced Optical Materials, 9 (12), Art.-Nr.: 2100479. doi:10.1002/adom.202100479

Revealing the internal luminescence quantum efficiency of perovskite films via accurate quantification of photon recycling
Fassl, P.; Lami, V.; Berger, F. J.; Falk, L. M.; Zaumseil, J.; Richards, B. S.; Howard, I. A.; Vaynzof, Y.; Paetzold, U. W.
2021. Matter, 4 (4), 1391–1412. doi:10.1016/j.matt.2021.01.019

Interplay of structural dynamics and electronic effects in an engineered assembly of pentacene in a metal–organic framework
Haldar, R.; Kozlowska, M.; Ganschow, M.; Ghosh, S.; Jakoby, M.; Chen, H.; Ghalami, F.; Xie, W.; c; Tsutsui, Y.; Freudenberg, J.; Seki, S.; Howard, I. A.; Richards, B. S.; Bunz, U. H. F.; Elstner, M.; Wenzel, W.; Wöll, C.
2021. Chemical science, 12 (12), 4477–4483. doi:10.1039/d0sc07073d

How free exciton-exciton annihilation lets bound exciton emission dominate the photoluminescence of 2D-perovskites under high-fluence pulsed excitation at cryogenic temperatures
Kaiser, M.; Li, Y.; Schwenzer, J.; Jakoby, M.; Allegro, I.; Gerhard, M.; Koch, M.; Ducinskas, A.; Richards, B. S.; Graetzel, M.; Milić, J. V.; Paetzold, U. W.; Howard, I. A.
2021. Journal of Applied Physics, 129 (12), Art.-Nr.: 123101. doi:10.1063/5.0037800

An up-conversion luminophore with high quantum yield and brightness based on BaF $_{2}$ :Yb $^{3 +}$ ,Er $^{3 +}$ single crystals
Madirov, E. I.; Konyushkin, V. A.; Nakladov, A. N.; Fedorov, P. P.; Bergfeldt, T.; Busko, D.; Howard, I. A.; Richards, B. S.; Kuznetsov, S. V.; Turshatov, A.
2021. Journal of materials chemistry / C, 9 (10), 3493–3503. doi:10.1039/d1tc00104c

Bimolecular and Auger Recombination in Phase-Stable Perovskite Thin Films from Cryogenic to Room Temperature and Their Effect on the Amplified Spontaneous Emission Threshold
Allegro, I.; Li, Y.; Richards, B. S.; Paetzold, U. W.; Lemmer, U.; Howard, I. A.
2021. The journal of physical chemistry letters, 12 (9), 2293–2298. doi:10.1021/acs.jpclett.1c00099

Bright constant color upconversion based on dual 980 and 1550 nm excitation of SrF $_{2}$ :Yb $^{3 +}$ , Er $^{3 +}$ and β-NaYF $_{4}$ :Yb $^{3 +}$ , Er $^{3 +}$ micropowders― considerations for persistence of vision displays
Joseph, R. E.; Hudry, D.; Busko, D.; Biner, D.; Turshatov, A.; Krämer, K.; Richards, B. S.; Howard, I. A.
2021. Optical materials, 111, Art.Nr. 110598. doi:10.1016/j.optmat.2020.110598

2020

Tuning Optical Properties by Controlled Aggregation: Electroluminescence Assisted by Thermally‐Activated Delayed Fluorescence from Thin Films of Crystalline Chromophores
Wöll, C.; Haldar, R.; Jakoby, M.; Kozlowska, M.; Khan, M. R.; Chen, H.; Pramudya, Y.; Richards, B. S.; Heinke, L.; Wenzel, W.; Odobel, F.; Diring, S.; Howard, I. A.; Lemmer, U.
2020. Chemistry - a European journal, 26 (71), 17016–17020. doi:10.1002/chem.202003712

A fully planar solar pumped laser based on a luminescent solar collector
Masuda, T.; Iyoda, M.; Yasumatsu, Y.; Dottermusch, S.; Howard, I. A.; Richards, B. S.; Bisson, J.-F.; Endo, M.
2020. Communications Physics, 3 (1), Article No. 60. doi:10.1038/s42005-020-0326-2

Crystalline assembly of perylene in metal–organic framework thin film: J-aggregate or excimer? Insight into the electronic structure
Kozlowska, M.; Pramudya, Y.; Jakoby, M.; Heidrich, S.; Pan, L.; Richards, B.; Howard, I.; Woell, C.; Haldar, R.; Wenzel, W.
2020. Journal of physics / Condensed matter, 33 (3), Art.Nr. 034001. doi:10.1088/1361-648X/abbc34

Phonon density of states in lanthanide-based nanocrystals
Li, Z. H.; Hudry, D.; Heid, R.; Said, A. H.; Le, M. D.; Popescu, R.; Gerthsen, D.; Merz, M.; Krämer, K. W.; Busko, D.; Howard, I. A.; Richards, B. S.; Weber, F.
2020. Physical review / B, 102 (16), Art.-Nr.: 165409. doi:10.1103/PhysRevB.102.165409

Inorganic fluorescent marker materials for identification of post-consumer plastic packaging
Woidasky, J.; Sander, I.; Schau, A.; Moesslein, J.; Wendler, P.; Wacker, D.; Gao, G.; Kirchenbauer, D.; Kumar, V.; Busko, D.; Howard, I. A.; Richards, B. S.; Turshatov, A.; Wiethoff, S.; Lang-Koetz, C.
2020. Resources, conservation and recycling, 161, Article no: 104976. doi:10.1016/j.resconrec.2020.104976

Spontaneous Enhancement of the Power Output in Surface-Passivated Triple-Cation Perovskite Solar Cells
Moghadamzadeh, S.; Gharibzadeh, S.; Jakoby, M.; Khan, M. R.; Haghighirad, A. A.; Howard, I. A.; Richards, B. S.; Lemmer, U.; Paetzold, U. W.
2020. 2020 47th IEEE Photovoltaic Specialists Conference (PVSC), 15 June - 21 August 2020, online, 1217–1219, Institute of Electrical and Electronics Engineers (IEEE). doi:10.1109/PVSC45281.2020.9300632

Solar powered fiber laser for energy conversion applications
Masuda, T.; Dottermusch, S.; Howard, I. A.; Richards, B. S.; Bisson, J.; Endo, M.
2020. CLEO: Applications and Technology : part of CLEO: 2020 : 10-15 May 2020, Washington, DC, United States, Art.Nr. AF3N.4, Optica Publishing Group (OSA). doi:10.1364/CLEO_AT.2020.AF3N.4

Guest-responsive polaritons in a porous framework: chromophoric sponges in optical QED cavities
Haldar, R.; Fu, Z.; Joseph, R.; Herrero, D.; Martín-Gomis, L.; Richards, B. S.; Howard, I. A.; Sastre-Santos, A.; Wöll, C.
2020. Chemical science, 11 (30), 7972–7978. doi:10.1039/d0sc02436h

Correction: Guest-responsive polaritons in a porous framework: chromophoric sponges in optical QED cavities
Haldar, R.; Fu, Z.; Joseph, R.; Herrero, D.; Martín-Gomis, L.; Richards, B. S.; Howard, I. A.; Sastre-Santos, Á.; Wöll, C.
2020. Chemical science, 11 (32), 8626. doi:10.1039/d0sc90163f

Smartphone‐Based Luminescent Thermometry via Temperature‐Sensitive Delayed Fluorescence from Gd $_{0}$ O $_{2}$ S:Eu $^{3 +}$
Katumo, N.; Gao, G.; Laufer, F.; Richards, B. S.; Howard, I. A.
2020. Advanced optical materials, 8 (19), Art.Nr. 2000507. doi:10.1002/adom.202000507

Sensitizing TADF Absorption Using Variable Length Oligo(phenylene ethynylene) Antennae
Franco, O.; Jakoby, M.; Schneider, R. V.; Hundemer, F.; Hahn, D.; Richards, B. S.; Bräse, S.; Meier, M. A. R.; Lemmer, U.; Howard, I. A.
2020. Frontiers in Chemistry, 8, Art.-Nr.: 126. doi:10.3389/fchem.2020.00126

Lanthanide Sensitizers for Large Anti-Stokes Shift Near-Infrared-to-Visible Triplet–Triplet Annihilation Photon Upconversion
Kiseleva, N.; Nazari, P.; Dee, C.; Busko, D.; Richards, B. S.; Seitz, M.; Howard, I. A.; Turshatov, A.
2020. The journal of physical chemistry letters, 11, 2477–2481. doi:10.1021/acs.jpclett.0c00221

Upconversion properties of SrF₂:Yb³⁺,Er³⁺ single crystals
Saleta Reig, D.; Grauel, B.; Konyushkin, V. A.; Fedorov, P. P.; Busko, D.; Howard, I. A.; Richards, B. S.; Resch-Genger, U.; Kuznetsov, S.; Turshatov, A.; Würth, C.
2020. Journal of materials chemistry / C, 8 (12), 4093–4101. doi:10.1039/C9TC06591A

Improved photon absorption in dye-functionalized silicon nanocrystals synthesized via microwave-assisted hydrosilylation
Beri, D.; Jakoby, M.; Howard, I. A.; Busko, D.; Richards, B. S.; Turshatov, A.
2020. Dalton transactions, 49 (7), 2290–2299. doi:10.1039/C9DT04497C

High-brightness Perovskite Light-emitting Diodes Using a Printable Silver Microflake Contact
Payandeh, M.; Ahmadi, V.; Arabpour Roghabadi, F.; Nazari, P.; Ansari, F.; Brenner, P.; Baeuerle, R.; jakoby, marius; Lemmer, U.; Howard, I. A.; Richards, B. S.; Paetzold, U. W.; Abdollahi Nejand, B.
2020. ACS applied materials & interfaces, 12 (10), 11428–11437. doi:10.1021/acsami.9b18527

Solution-processed and evaporated C $_{60}$ interlayers for improved charge transport in perovskite photovoltaics
Rueda-Delgado, D.; Hossain, I. M.; Jakoby, M.; Schwenzer, J. A.; Abzieher, T.; Howard, I. A.; Richards, B. S.; Lemmer, U.; Paetzold, U. W.
2020. Organic electronics, 77, Article: 105526. doi:10.1016/j.orgel.2019.105526

Vacuum‐Assisted Growth of Low‐Bandgap Thin Films (FA $_{0.8}$ MA $_{0.2}$ Sn $_{0.5}$ Pb $_{0.5}$ I $_{3}$ ) for All‐Perovskite Tandem Solar Cells
Abdollahi Nejand, B.; Hossain, I. M.; Jakoby, M.; Moghadamzadeh, S.; Abzieher, T.; Gharibzadeh, S.; Schwenzer, J. A.; Nazari, P.; Schackmar, F.; Hauschild, D.; Weinhardt, L.; Lemmer, U.; Richards, B. S.; Howard, I. A.; Paetzold, U. W.
2020. Advanced energy materials, 10 (5), Article: 1902583. doi:10.1002/aenm.201902583

2019

A de novo strategy for predictive crystal engineering to tune excitonic coupling
Haldar, R.; Mazel, A.; Krstić, M.; Zhang, Q.; Jakoby, M.; Howard, I. A.; Richards, B. S.; Jung, N.; Jacquemin, D.; Diring, S.; Wenzel, W.; Odobel, F.; Wöll, C.
2019. Nature Communications, 10 (1), Art.Nr. 2048. doi:10.1038/s41467-019-10011-8

Comment on “Room-Temperature Continuous-Wave Operation of Organometal Halide Perovskite Lasers”
Brenner, P.; Paetzold, U. W.; Turnbull, G. A.; Giebink, N. C.; Samuel, I. D. W.; Lemmer, U.; Howard, I. A.
2019. ACS nano, 13 (11), 12257–12258. doi:10.1021/acsnano.9b00133

Coated and Printed Perovskites for Photovoltaic Applications
Howard, I. A.; Abzieher, T.; Hossain, I. M.; Eggers, H.; Schackmar, F.; Ternes, S.; Richards, B. S.; Lemmer, U.; Paetzold, U. W.
2019. Advanced materials, 31 (26), Art.Nr. 1806702. doi:10.1002/adma.201806702

Structure–Property Relationships in Lanthanide‐Doped Upconverting Nanocrystals: Recent Advances in Understanding Core–Shell Structures
Hudry, D.; Howard, I. A.; Popescu, R.; Gerthsen, D.; Richards, B. S.
2019. Advanced materials, 31 (26), Art.Nr. 1900623. doi:10.1002/adma.201900623

Perovskite Solar Cells: Record Open‐Circuit Voltage Wide‐Bandgap Perovskite Solar Cells Utilizing 2D/3D Perovskite Heterostructure
Gharibzadeh, S.; Abdollahi Nejand, B.; Jakoby, M.; Abzieher, T.; Hauschild, D.; Moghadamzadeh, S.; Schwenzer, J. A.; Brenner, P.; Schmager, R.; Haghighirad, A. A.; Weinhardt, L.; Lemmer, U.; Richards, B. S.; Howard, I. A.; Paetzold, U. W.
2019. Advanced energy materials, 9 (21), 1970079. doi:10.1002/aenm.201970079

Continuous wave amplified spontaneous emission in phase-stable lead halide perovskites
Brenner, P.; Bar-On, O.; Jakoby, M.; Allegro, I.; Richards, B. S.; Paetzold, U. W.; Howard, I. A.; Scheuer, J.; Lemmer, U.
2019. Nature Communications, 10 (1), Article-Nr.: 988. doi:10.1038/s41467-019-08929-0

Continuous wave amplified spontaneous emission in phase-stable triple cation lead halide perovskite thin films
Allegro, I.; Brenner, P.; Bar-On, O.; Jakoby, M.; Richards, B. S.; Paetzold, U. W.; Howard, I. A.; Scheuer, J.; Lemmer, U.
2019. 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC): Munich, International Congress Centre (ICM), Germany, 23-27 June 2019, Institute of Electrical and Electronics Engineers (IEEE). doi:10.1109/CLEOE-EQEC.2019.8871688

Spontaneous Enhancement of the Stable Power Conversion Efficiency in Perovskite Solar Cells
Moghadamzadeh, S.; Hossain, I.; Jakoby, M.; Abdollahi Nejand, B.; Rueda-Delgado, D.; Schwenzer, J. A.; Gharibzadeh, S.; Abzieher, T.; Khan, M. R.; Haghighirad, A. A.; Howard, I. A.; Richards, B. S.; Lemmer, U.; Paetzold, U. W.
2019. Journal of materials chemistry / A, 8 (2), 670–682. doi:10.1039/C9TA09584E

Investigations of singlet and triplet diffusion in thermally activated delayed-fluorescence emitters: Implications for hyperfluorescence
Jakoby, M.; Richards, B. S.; Lemmer, U.; Howard, I. A.
2019. Physical review / B, 100 (4), Art. Nr.: 045303. doi:10.1103/PhysRevB.100.045303

Critical Power Density: A Metric to Compare the Excitation Power Density Dependence of Photon Upconversion in Different Inorganic Host Materials
Joseph, R. E.; Jiménez, C.; Hudry, D.; Gao, G.; Busko, D.; Biner, D.; Turshatov, A.; Krämer, K.; Richards, B. S.; Howard, I. A.
2019. The journal of physical chemistry <Washington, DC> / A, 123 (31), 6799–6811. doi:10.1021/acs.jpca.9b03851

Continuous Wave Amplified Spontaneous Emission from Mixed Cation Perovskite devices
Brenner, P.; Bar-On, O.; Jakoby, M.; Allegro, I.; Richards, B. S.; Paetzold, U. W.; Howard, I. A.; Scheuer, J.; Lemmer, U.
2019. Conference on Lasers and Electro-Optics, JTu2A.71, Optica Publishing Group (OSA). doi:10.1364/CLEO_AT.2019.JTu2A.71

An enhanced energy migration strategy in upconverting nanocrystals: Color-tuning with high quantum yield
Hudry, D.; Busko, D.; Popescu, R.; Gerthsen, D.; Howard, I. A.; Richards, B. S.
2019. Journal of materials chemistry / C, 7 (24), 7371–7377. doi:10.1039/c9tc01567a

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks
Hamer, S.; Röhricht, F.; Jakoby, M.; Howard, I. A.; Zhang, X.; Näther, C.; Herges, R.
2019. Beilstein journal of organic chemistry, 15, 1331–1338. doi:10.3762/bjoc.15.132

Highly Efficient One-Dimensional Triplet Exciton Transport in a Palladium-Porphyrin-Based Surface-Anchored Metal-Organic Framework
Adams, M.; Kozlowska, M.; Baroni, N.; Oldenburg, M.; Ma, R.; Busko, D.; Turshatov, A.; Emandi, G.; Senge, M. O.; Haldar, R.; Wöll, C.; Nienhaus, G. U.; Richards, B. S.; Howard, I. A.
2019. ACS applied materials & interfaces, 11 (17), 15688–15697. doi:10.1021/acsami.9b03079

Record Open‐Circuit Voltage Wide‐Bandgap Perovskite Solar Cells Utilizing 2D/3D Perovskite Heterostructure
Gharibzadeh, S.; Abdollahi Nejand, B.; Jakoby, M.; Abzieher, T.; Hauschild, D.; Moghadamzadeh, S.; Schwenzer, J. A.; Brenner, P.; Schmager, R.; Haghighirad, A. A.; Weinhardt, L.; Lemmer, U.; Richards, B. S.; Howard, I. A.; Paetzold, U. W.
2019. Advanced energy materials, 9 (21), Article: 1803699. doi:10.1002/aenm.201803699

High Quantum Yield Single-Band Green Upconversion in La₂O₃:Yb³⁺, Ho³⁺ Microcrystals for Anticounterfeiting and Plastic Recycling
Gao, G.; Busko, D.; Joseph, R.; Turshatov, A.; Howard, I. A.; Richards, B. S.
2019. Particle & Particle Systems Characterization, 36 (3), Art.-Nr.: 1800462. doi:10.1002/ppsc.201800462

2018

Anisotropic energy transfer in crystalline chromophore assemblies
Haldar, R.; Jakoby, M.; Mazel, A.; Zhang, Q.; Welle, A.; Mohamed, T.; Krolla, P.; Wenzel, W.; Diring, S.; Odobel, F.; Richards, B. S.; Howard, I. A.; Wöll, C.
2018. Nature Communications, 9 (1), Art.Nr. 4332. doi:10.1038/s41467-018-06829-3

Probing the pathways of free charge generation in organic bulk heterojunction solar cells
Kurpiers, J.; Ferron, T.; Roland, S.; Jakoby, M.; Thiede, T.; Jaiser, F.; Albrecht, S.; Janietz, S.; Collins, B. A.; Howard, I. A.; Neher, D.
2018. Nature Communications, 9 (1), Article no 2038. doi:10.1038/s41467-018-04386-3

Highly Efficient La₂O₃:Yb³⁺,Tm³⁺ Single-Band NIR-to-NIR Upconverting Microcrystals for Anti-Counterfeiting Applications
Gao, G.; Busko, D.; Joseph, R.; Howard, I. A.; Turshatov, A.; Richards, B. S.
2018. ACS applied materials & interfaces, 10 (46), 39851–39859. doi:10.1021/acsami.8b11196

Inkjet-Printed Photoluminescent Patterns of Aggregation-Induced-Emission Chromophores on Surface-Anchored Metal–Organic Frameworks
Baroni, N.; Turshatov, A.; Adams, M.; Dolgopolova, E. A.; Schlisske, S.; Hernandez-Sosa, G.; Wöll, C.; Shustova, N. B.; Richards, B. S.; Howard, I. A.
2018. ACS applied materials & interfaces, 10 (30), 25754–25762. doi:10.1021/acsami.8b05568

A method for correcting the excitation power density dependence of upconversion emission due to laser-induced heating
Joseph, R. E.; Busko, D.; Hudry, D.; Gao, G.; Biner, D.; Krämer, K.; Turshatov, A.; Richards, B. S.; Howard, I. A.
2018. Optical materials, 82, 65–70. doi:10.1016/j.optmat.2018.05.025

Interface disorder in large single- and multi-shell upconverting nanocrystals
Hudry, D.; Popescu, R.; Busko, D.; Diaz-Lopez, M.; Abeykoon, M.; Bordet, P.; Gerthsen, D.; Howard, I. A.; Richards, B. S.
2018. Journal of materials chemistry / C, 2019 (7), 1164–1172. doi:10.1039/C8TC05130E

A Novel Route to Plastics Recycling via Unique, Background-free, Micro-scale Photonic Markers
Richards, B. S.; Busko, D.; Gao, G.; Hudry, D.; Howard, I. A.; Turshatov, A.
2018. Optics and Photonics for Energy and the Environment, Singapore, 5–8 November 2018, EM2A.4, Optica Publishing Group (OSA). doi:10.1364/EE.2018.EM2A.4

Reaction of porphyrin-based surface-anchored metal-organic frameworks to prolonged illumination
Adams, M.; Baroni, N.; Oldenburg, M.; Kraffert, F.; Behrends, J.; MacQueen, R. W.; Haldar, R.; Busko, D.; Turshatov, A.; Emandi, G.; Senge, M. O.; Wöll, C.; Lips, K.; Richards, B. S.; Howard, I. A.
2018. Physical chemistry, chemical physics, 46, 29142–29151. doi:10.1039/C8CP05254A

Absolute upconversion quantum yields of blue-emitting LiYF4:Yb3+,Tm3+ upconverting nanoparticles
Meijer, M. S.; Rojas-Gutierrez, P. A.; Busko, D.; Howard, I. A.; Frenzel, F.; Würth, C.; Resch-Genger, U.; Richards, B. S.; Turshatov, A.; Capobianco, J. A.; Bonnet, S.
2018. Physical chemistry, chemical physics, 20, 22556–22562. doi:10.1039/C8CP03935F

Up-conversion quantum yields of SrF2:Yb3+,Er3+ sub-micron particles prepared by precipitation from aqueous solution
Kuznetsov, S.; Ermakova, Y.; Voronov, V.; Fedorov, P.; Busko, D.; Howard, I. A.; Richards, B. S.; Turshatov, A.
2018. Journal of materials chemistry / C, 6 (3), 598–604. doi:10.1039/C7TC04913G

Enhancing the photoluminescence of surface anchored metal–organic frameworks: mixed linkers and efficient acceptors
Oldenburg, M.; Turshatov, A.; Busko, D.; Jakoby, M.; Haldar, R.; Chen, K.; Emandi, G.; Senge, M. O.; Wöll, C.; Hodgkiss, J. M.; Richards, B. S.; Howard, I. A.
2018. Physical chemistry, chemical physics, 20 (17), 11564–11576. doi:10.1039/C7CP08452H

Wide-range non-contact fluorescence intensity ratio thermometer based on Yb³⁺/Nd³⁺ co-doped La₂O₃ microcrystals operating from 290 to 1230 K
Gao, G.; Busko, D.; Kauffmann-Weiss, S.; Turshatov, A.; Howard, I. A.; Richards, B. S.
2018. Journal of materials chemistry / C, 6 (15), 4163–4170. doi:10.1039/C8TC00782A

Highly photoluminescent and stable silicon nanocrystals functionalized via microwave-assisted hydrosilylation
Beri, D.; Busko, D.; Mazilkin, A.; Howard, I. A.; Richards, B. S.; Turshatov, A.
2018. RSC Advances, 8 (18), 9979–9984. doi:10.1039/C7RA13577G

The Janus-faced chromophore : A donor-acceptor dyad with dual performance in photon up-conversion
Kiseleva, N.; Filatov, M. A.; Oldenburg, M.; Busko, D.; Jakoby, M.; Howard, I. A.; Richards, B. S.; Senge, M. O.; Borisov, S. M.; Turshatov, A.
2018. Chemical communications, 54 (13), 1607–1610. doi:10.1039/c7cc08930a

Inkjet-printed perovskite distributed feedback lasers
Mathies, F.; Brenner, P.; Hernandez-Sosa, G.; Howard, I. A.; Paetzold, U. W.; Lemmer, U.
2018. Optics express, 26 (2), A144 - A152. doi:10.1364/OE.26.00A144

2017

N-Heteroacenes as a New Class of Non-Fullerene Electron Acceptors for Organic Bulk-Heterojunction Photovoltaic Devices
Lami, V.; Leibold, D.; Fassl, P.; Hofstetter, Y. J.; Becker-Koch, D.; Biegger, P.; Paulus, F.; Hopkinson, P. E.; Adams, M.; Bunz, U. H. F.; Huettner, S.; Howard, I.; Bakulin, A. A.; Vaynzof, Y.
2017. Solar RRL, 1 (6), Art.Nr. 1700053. doi:10.1002/solr.201700053

Scalable and low cost fabrication methods for wavelength tunable solution processed perovskite distributed feedback lasers
Brenner, P.; Mathies, F.; Kapp, D.; Paetzold, U.; Quintilla, A.; Hernandez-Sosa, G.; Howard, I.; Lemmer, U.
2017. Proceedings of the European Conference on Lasers and Electro-Optics 2017, Munich, Germany, 25th - 29th June 2017, Art.Nr. JSV_3_2, Optica Publishing Group (OSA)

Relating Structure to Efficiency in Surfactant-Free Polymer/Fullerene Nanoparticle-Based Organic Solar Cells
Gärtner, S.; Clulow, A. J.; Howard, I. A.; Gilbert, E. P.; Burn, P. L.; Gentle, I. R.; Colsmann, A.
2017. ACS applied materials & interfaces, 9 (49), 42986–42995. doi:10.1021/acsami.7b15601

Finely-tuned NIR-to-visible up-conversion in La2O3:Yb3+,Er3+ microcrystals with high quantum yield
Gao, G.; Busko, D.; Kauffmann-Weiss, S.; Turshatov, A.; Howard, I. A.; Richards, B. S.
2017. Journal of materials chemistry / C, 5 (42), 11010–11017. doi:10.1039/C6TC05322J

Triple cation mixed-halide perovskites for tunable lasers
Brenner, P.; Glöckler, T.; Rueda-Delgado, D.; Abzieher, T.; Jakoby, M.; Richards, B. S.; Paetzold, U. W.; Howard, I. A.; Lemmer, U.
2017. Optical materials express, 7 (11), 4082–4094. doi:10.1364/OME.7.004082

Excitonically Coupled States in Crystalline Coordination Networks
Haldar, R.; Mazel, A.; Joseph, R.; Adams, M.; Howard, I. A.; Richards, B. S.; Tsotsalas, M.; Redel, E.; Diring, S.; Odobel, F.; Wöll, C.
2017. Chemistry - a European journal, 23 (57), 14316–14322. doi:10.1002/chem.201702968

Facile loading of thin-film surface-anchored metal-organic frameworks with Lewis-base guest molecules
Baroni, N.; Turshatov, A.; Oldenburg, M.; Busko, D.; Adams, M.; Haldar, R.; Welle, A.; Redel, E.; Wöll, C.; Richards, B. S.; Howard, I. A.
2017. Materials chemistry frontiers, 1 (9), 1888–1894. doi:10.1039/C7QM00142H

Up-Conversion Fluorescent Labels for Plastic Recycling: A Review
Gao, G.; Turshatov, A.; Howard, I. A.; Busko, D.; Joseph, R.; Hudry, D.; Richards, B. S.
2017. Advanced Sustainable Systems, 1 (5), Art.Nr. 1600033. doi:10.1002/adsu.201600033

Identifying Charge-Transfer States in Polymer:Fullerene Heterojunctions by Their Emission Polarization Anisotropy
Arndt, A. P.; Gerhard, M.; Koch, M.; Lemmer, U.; Howard, I. A.
2017. The journal of physical chemistry <Washington, DC> / C, 121 (11), 6357–6364. doi:10.1021/acs.jpcc.6b12853

Field-induced exciton dissociation in PTB7-based organic solar cells
Gerhard, M.; Arndt, A. P.; Bilal, M.; Lemmer, U.; Koch, M.; Howard, I. A.
2017. Physical review / B, 95 (19), Art.Nr. 195301. doi:10.1103/PhysRevB.95.195301

Room-Temperature High-Efficiency Solid-State Triplet-Triplet Annihilation Up-Conversion in Amorphous Poly(olefin sulfone)s
Turshatov, A.; Busko, D.; Kiseleva, N.; Grage, S. L.; Howard, I. A.; Richards, B. S.
2017. ACS applied materials & interfaces, 9 (9), 8280–8286. doi:10.1021/acsami.6b12625

2016

Bragg Stacks Enhancing Upconversion for Photovoltaics: A Theoretical And Experimental Analysis
Hofmann, C. L.; Fischer, S.; Reitz, C.; Mondon, A.; Busko, D.; Howard, I.; Richards, B. S.; Goldschmidt, J. C.
2016. Light, Energy and the Environment Congress, November 14-17, 2016, Leipzig, Germany, PTh4A.5, Optica Publishing Group (OSA). doi:10.1364/PV.2016.PTh4A.5

Highly stable solution processed metal-halide perovskite lasers on nanoimprinted distributed feedback structures
Brenner, P.; Stulz, M.; Kapp, D.; Abzieher, T.; Paetzold, U. W.; Quintilla, A.; Howard, I. A.; Kalt, H.; Lemmer, U.
2016. Applied physics letters, 109 (14), 141106. doi:10.1063/1.4963893

Photon Upconversion at Crystalline Organic-Organic Heterojunctions
Oldenburg, M.; Turshatov, A.; Busko, D.; Wollgarten, S.; Adams, M.; Baroni, N.; Welle, A.; Redel, E.; Wöll, C.; Richards, B. S.; Howard, I. A.
2016. Advanced materials, 28 (38), 8477–8482. doi:10.1002/adma.201601718

Electronic transfer across crystalline thin-film surface anchored metal-organic framework (SURMOF) heterojunctions
Oldenburg, M.; Howard, I. A.; Turshatov, A.; Baroni, N.; Wollgarten, S.; Redel, E.; Wöll, C.; Richards, B. S.
2016. SPIE Photonics Europe, Brussels, B, 3.-7. April 2016

Active heterostructure of crystalline thin-film surface anchored metal-organic frameworks for optoelectronic applications
Oldenburg, M.; Howard, I. A.; Turshatov, A.; Baroni, N.; Wollgarten, S.; Redel, E.; Wöll, C.
2016. 80. Jahrestagung der DPG und DPG-Frühjahrstagung der Sektion Kondensierte Materie, Fachverband Chemische Physik und Polymerphysik, Regensburg, 6.-11.März 2016. Verhandlungen der Deutschen Physikalischen Gesellschaft, R.6, B.51(2016) CPP32.9, H37

Loss mechanisms in organic solar cells based on perylene diimide acceptors studied by time-resolved photoluminescence
Gerhard, M.; Gehring, D.; Howard, I. A.; Arndt, A. P.; Bilal, M.; Rahimi-Iman, A.; Lemmer, U.; Laquai, F.; Koch, M.
2016. Organic Photonics VII. Ed.: D. Cheyns, 98950H, Society of Photo-optical Instrumentation Engineers (SPIE). doi:10.1117/12.2227672

2015

Temperature- and energy-dependent separation of charge-transfer states in PTB7-based organic solar cells
Gerhard, M.; Arndt, A. P.; Howard, I. A.; Rahimi-Iman, A.; Lemmer, U.; Koch, M.
2015. The journal of physical chemistry <Washington, DC> / C, 119 (51), 28309–28318. doi:10.1021/acs.jpcc.5b09842

Photoinduzierte Erzeugung von Ladungsträgern in epitaktischen MOF-Dünnschichten: hohe Leistung aufgrund einer indirekten elektronischen Bandlücke?
Liu, J.; Zhou, W.; Liu, J.; Howard, I.; Kilibarda, G.; Schlabach, S.; Coupry, D.; Addicoat, M.; Yoneda, S.; Tsutsui, Y.; Sakurai, T.; Seki, S.; Wang, Z.; Lindemann, P.; Redel, E.; Heine, T.; Wöll, C.
2015. Angewandte Chemie, 127, 7549–7553. doi:10.1002/ange.201501862

Photoinduced charge-carrier generation in epitaxial MOF thin films: High efficiency as a result of an indirect electronic band gap?
Liu, J.; Zhou, W.; Liu, J.; Howard, I.; Kilibarda, G.; Schlabach, S.; Coupry, D.; Addicoat, M.; Yoneda, S.; Tsutsui, Y.; Sakurai, T.; Seki, S.; Wang, Z.; Lindemann, P.; Redel, E.; Heine, T.; Wöll, C.
2015. Angewandte Chemie / International edition, 54 (25), 7441–7445. doi:10.1002/anie.201501862

The impact of donor-acceptor phase separation on the charge carrier dynamics in pBTTT:PCBM photovoltaic blends
Gehrig, D. W.; Howard, I. A.; Sweetnam, S.; Burke, T. M.; McGehee, M.; Laquai, F.
2015. Macromolecular rapid communications, 36 (11), 1054–1060. doi:10.1002/marc.201500112

Time-resolved charge-transfer state emission in organic solar cells : Temperature and blend composition dependences of interfacial traps
Arndt, A. P.; Gerhard, M.; Quintilla, A.; Howard, I. A.; Koch, M. W.; Lemmer, U.
2015. The journal of physical chemistry <Washington, DC> / C, 119 (24), 13516–13523. doi:10.1021/acs.jpcc.5b03507

2014

Control of charge generation and recombination in ternary polymer/polymer:fullerene photovoltaic blends using amorphous and semi-crystalline copolymers as donors
Mangold, H.; Bakulin, A. A.; Howard, I. A.; Kästner, C.; Egbe, D. A. M.; Hoppe, H.; Laquai, F.
2014. Physical chemistry, chemical physics, 16, 20329–20337. doi:10.1039/C4CP01883D