Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 20: Fundamentals of Perovskite Photovoltaics II (joint session CPP/DS/HL)

HL 20.2: Invited Talk

Monday, March 20, 2017, 15:30–16:00, ZEU 222

Photon recycling in hybrid lead-halide perovskite semiconductors — •Felix Deschler — University of Cambridge, Cambridge, UK

We discuss the effect of photon recycling on the externally measured radiative recombination rates in hybrid perovskites. By combining transient absorption with transient photoluminescence (PL) data, we distinguish radiative from non-radiative processes and find that the PL originates from a bimolecular process for all investigated carrier densities. We measure external photoluminescence quantum efficiencies (PLQEs) under continuous-wave and pulsed excitation. Taking into account photon recycling, we connect the externally measured radiative efficiencies with the actual internal values, and derive internal PLQEs exceeding 80%.

We map the propagation of photo-generated luminescence and charges from a local photo-excitation spot in thin films of lead tri-iodide perovskites using a confocal microscopy setup. We observed regenerated PL emission at distances as far as 50 micrometers away from photo-excitation. We map the internal photon distribution in the film and find that, over these distances, the peak of the internal photon spectrum red-shifts from 765 to >800 nanometers. We build a lateral-contact solar cell with selective electron- and hole-collecting contacts, using a combination of photo-lithography and electro-deposition. We used these devices as a platform to study photocurrent propagation and found that charge extraction can be achieved well beyond 50 micrometers away from the excitation.