Univ.-Prof. Dr. rer. nat. Thomas Riedl

Organic/Inorganic Hybrid Perovskites

Power conversion efficiencies of organic−inorganic hybrid perovskite solar cells (PSCs) have rapidly increased to a level >24%. Aside from photovoltaics, this family of materials also holds great promise for future applications in light-emitting diodes (LEDs) and lasers.

Semitransparent solar cells are of interest for application in tandem solar cells and building‐integrated photovoltaics. We fabricated robust PSCs with semitransparent top electrodes, where an ultrathin Ag layer is sandwiched between SnOx grown by low‐temperature atomic layer deposition. The SnOx forms an electrically conductive permeation barrier, which protects both the perovskite and the ultrathin silver electrode against the detrimental impact of moisture. At the same time, the SnOx cladding layer underneath the ultra‐thin Ag layer shields the metal against corrosive halide compounds leaking out of the perovskite.

Hybrid perovskites are sometimes also considered as “soft materials”. As a side remark, it has been shown that similar to other soft materials, MAPbI3 could directly be pattered by thermal nanoimprint (NIL) at low temperatures (100°C). A notable effect of this imprinting process was a substantial flattening of the initially very rough polycrystalline perovskite layers to thin films consisting of large crystals on the order of tens of microns with a surface roughness below 1 nm (rms).

Photonic nanostructures are created in organo‐metal halide perovskites by thermal nanoimprint lithography. 2D photonic‐crystal lasers are prepared by direct thermal nanoimprint lithography into a spin‐coated layer of a MAPbI3 perovskite, which is beneficial for low propagation losses of wave‐guided optical modes in the perovskite layer. Moreover, surface defects which cause substantial recombination and luminescence quenching are eliminated by the recrystallization upon thermal imprint. The resulting 2D‐PC lasers show low lasing thresholds.

The first DFB lasers based on MAPbBr3 thin films, with a linear photonic grating imprinted into the MAPbBr3 active layers is presented in the following. High-Q Bragg resonator gratings with a periodicity of 300 nm are directly patterned by thermal nanoimprinting. In optically pumped DFB laser structures, very low lasing thresholds of 3.4 μJ cm−2 are achieved.

Publications

N. Pourdavoud, A. Mayer, M. Buchmüller, K. Brinkmann, T. Häger, T. Hu, R. Heiderhoff, I. Shutsko, P. Görrn, Y. Chen, H.-C. Scheer, and T. Riedl:
Distributed Feedback Lasers Based on MAPbBr3
Adv. Mater. Technol. 3, 1700253 (2018).

S. Olthof, K. Brinkmann, T. Hu, K. Meerholz, T. Riedl:
Metal Oxide Layers in Perovskite Solar Cells: a Double-Edged Sword (invited)
nanoGe Fall Meeting, Torremolinos (Spain), S5.6-O3 (2018).

L. Hoffmann, K. Brinkmann, T. Hasselmann, J. Malerczyk, T. Becker, D. Theirich, I. Shutsko, P. Görrn, T. Riedl:
Atmospheric pressure spatial ALD of SnOx for perovskite solar cells (invited)
E-MRS Fall Meeting, Warsaw (Poland), N.6b.4 (2018).

N. Pourdavoud, A. Mayer, T. Haeger, R. Heiderhoff, I. Shutsko, H.-C. Scheer, P. Görrn, and T. Riedl:
Ultra-smooth perovskite thin films for lasers (invited)
SPIE Optics and Photonics, San Diego (USA), 107240C (2018).

T. Riedl:
Transparent Materials for Perovskite (Opto-)electronics (invited)
8th Forum on New Materials - CIMTEC 2018, Perugia (Italy), FJ-3:IL05 (2018)

R. Heiderhoff, T. Haeger, N. Pourdavoud, T. Hu, M. Al-Khafaji, A. Mayer, Y. Chen, H.-C. Scheer, and T. Riedl:
Thermal Conductivity of Methylammonium Lead Halide Perovskite Single Crystals and Thin Films – A Comparative Study
J. Phys. Chem. C 121, 28306 (2017).

A. Mayer, M. Buchmüller, S. Wang, C. Steinberg, M. Papenheim, H.-C. Scheer, N. Pourdavoud, T. Haeger, and T. Riedl:
Thermal nanoimprint to improve the morphology of MAPbX3
J. Vac. Sci. & Technol. B 35, 06G803 (2017).

T. Hu, T. Becker, N. Pourdavoud, J. Zhao, K. Brinkmann, R. Heiderhoff, T. Gahlmann, Z. Huang, S. Olthof, K. Meerholz, D. Többens, B. Cheng, Y. Chen, and T. Riedl:
Indium-Free Perovskite Solar Cells Enabled by Impermeable Tin-Oxide Electron Extraction Layers
Adv. Mater. 29, 1606656 (2017).

J. Zhao, K. Brinkmann, T. Hu, N. Pourdavoud, T. Becker, T. Gahlmann, R. Heiderhoff, A. Polywka, P. Görrn, Y. Chen, B. Cheng, and T. Riedl:
Self-Encapsulating Thermostable and Air-Resilient Semitransparent Perovskite Solar Cells
Adv. Energy Mater. 7, 1602599 (2017).

N. Pourdavoud, S. Wang, A. Mayer, T. Hu, Y. Chen, A. Marianovich, W. Kowalsky, R. Heiderhoff, H.-C. Scheer, and T. Riedl:
Photonic Nanostructures Patterned by Thermal Nanoimprint Directly into Organo-Metal Halide Perovskites
Adv. Mater. 29, 1605003 (2017).

K. Brinkmann, J. Zhao, N. Pourdavoud, T. Becker, T. Hu, S. Olthof, K. Meerholz, L. Hoffmann, T. Gahlmann, R. Heiderhoff, M. F. Oszajca, N. A. Luechinger, D. Rogalla, Y. Chen, B. Cheng, and T. Riedl:
Suppressed decomposition of organo-metal halide perovskites by impermeable electron extraction layers in inverted solar cells
Nature Communications 7, 13938 (2017).

K. O. Brinkmann, J. Zhao, T. Hu, N. Pourdavoud, T. Gahlmann, R. Heiderhoff, S. Olthof, K. Meerholz, A. Polywka, B. Cheng, Y Chen, P. Görrn and T. Riedl:
Self-Encapsulating Air-Resilent Semitransparent Perovskite Solar Cells with Superior Thermal Stability Beyond 2000h
MRS Spring Meeting, Phoenix (USA) ES1.2.10 (2017).

N. Pourdavoud, A. Mayer, S. Wang, T. Hu, J. Zhou, K. Brinkmann, R. Heiderhoff, A. Marianowich, H.-C. Scheer, T. Riedl:
Photonic nanopatterns in organo-metal halide perovskites by thermal nanoimprint lithography (invited)
SPIE Optics and Photonics, San Diego (USA) 10363-32 (2017).

K. O. Brinkmann, J. Zhao, T. Hu, T. Becker, N. Pourdavoud, S. Olthof, K. Meerholz, L. Hoffmann, T. Gahlmann, R. Heiderhoff, M. Oszajca, D. Rogalla, N. A. Lüchinger, Y. Chen, B. Cheng, T. Riedl:
Pushing the lifetime of perovskite solar cell beyond 4500 h by the use of impermeable tin oxide electron extraction layers
SPIE Optics and Photonics, San Diego (USA) 10363-32 (2017).

N. Pourdavoud, A. Mayer, S. Wang ,M. Buchmüller, K. Brinkmann, T. Haeger, T. Hu, R. Heiderhoff, A. Marianovich, I. Shutsko, P. Görrn,Y. Chen, W. Kowalsky, H.-C. Scheer, T. Riedl:
Low-threshold Distributed Feedback Lasers Prepared By Direct Thermal Nanoimprint Of Resonator Gratings Into Organo-metal Halide Perovskites
(Nature Photonics Best Student Paper Award)
Photonics @ SG, Singapore (Singapore) 3-1D-5 (2017).

N. Pourdavoud, A. Mayer, R. Heiderhoff, H.C. Scheer, T. Riedl:
NIR Lasing in Hybrid Metal-Halide Perovskites (invited)
E-MRS Fall Meeting, Warsaw (Poland) R02.1 (2017).

L. Hoffmann, K. O. Brinkmann, J. Zhao, T. Hu, D. Schlamm, J. Malerczyk, T. Becker, D. Theirich, S. Olthof, K. Meerholz, H. Gargouri, Y. Chen, B. Cheng, T. Riedl:
ALD-Tin Oxide as Impermeable Electron Extraction Layers for Temperature Stable Roll-Ro-Roll-Compatible Perovskite Solar Cells
17th Conference on Atomic Layer Deposition, Denver (USA) AA1-TuA-11 (2017).

K. O. Brinkmann, T. Hu, T. Becker, N. Pourdavoud, J. Zhao, R. Heiderhoff, T. Gahlmann, Z. Huang, S. Olthof, K. Meerholz, D. Többens, B. Cheng, Y. Chen, T. Riedl:
Interface Electronic Structure of ALD-Grown SnOx and MAPbI3 in In-Free Perovskite Solar Cell
10th International Summit on Stability of Organic and Perovskite Solar Cells (ISOS-10), (Malta) ID13 (2017).

K. O. Brinkmann, L. Hoffmann, J. Malerczyk, T. Becker, D. Theirich, T. Riedl:
Spatial Atomic Layer Deposition of Impermeable Tin Oxide Electron Extraction Layers - Towards Roll-To-Roll manufacturing of Temperature Stable Perovskite Solar Cells
MRS Fall Meeting, Boston (USA) ES01.03.20 (2017).

N. Pourdavoud, A. Mayer, M. Buchmüller, K. Brinkmann, T. Häger, T. Hu, R. Heiderhoff, I. Shutsko, P. Görrn, Y. Chen, H.-C. Scheer, and T. Riedl:
Low-Threshold Distributed Feedback Lasers Based on Thermally Imprinted MAPbBr3
MRS Fall Meeting, Boston (USA) ES01.12.09 (2017).

T. Riedl:
Organo-Metal Halide Perovskites – ‘Novel’ Semiconductors for Optoelectronic Applications (invited)
Resource Chemistry Workshop, Shanghai (China), 17 (2017).

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