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HL: Fachverband Halbleiterphysik
HL 41: Perovskite and photovoltaics III (joint session HL/CPP)
HL 41.9: Vortrag
Mittwoch, 18. März 2020, 12:00–12:15, POT 251
Combined Multi-Photon-Excitation and Multi-Exciton-Generation Processes in CsPbBr3 Supercrystals — •Anja Barfüßer1, Alexander F. Richter1, Aurora Manzi1, Shixun Wang2, He Huang1, Andrey L. Rogach2, and Jochen Feldmann1 — 1Chair for Photonics and Optoelectronics, Nano-Institute Munich and Department of Physics, Ludwig-Maximilians-Universität (LMU), Königinstr. 10, 80539 Munich, Germany — 2Department of Materials Science and Engineering and Centre for Functional Photonics (CFP), City University of Hong Kong, Kowloon, Hong Kong
A fundamental problem limiting the power conversion efficiency of solar cells are photons with energies below the band gap, as they cannot be absorbed by linear processes, and above the band gap, as the excess energy typically is lost as heat. Multi-photon-excitation (MPE) and multi-exciton-generation (MEG) target this issue. Up to now, these processes have only been observed independently. Here, their combined effect is demonstrated for bulk-like CsPbBr3 perovskite nanocubes forming a superlattice. For below-band-gap excitation energies (0.5-0.8 Eg) nonlinear absorption is observed. Interestingly, when the energy of multiple below-band-gap photons resonantly matches the energy of multiple excitons, a strong photoluminescence enhancement of up to 105 takes place. Excitation power dependent measurements reveal a high-order absorption process deviating from the typical two-photon absorption.