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Proceedings Paper

Photon recycling in Lead-Iodide Perovskite solar cells (Conference Presentation)
Author(s): Luis Pazos; Monika Szummilo; Robin Lamboll; Johannes M. Richter; Micaela Crespo-Quesada; Mojtaba Abdi-Jalebi; Harry J. Beeson; Milan Vrucinic; Mejd Alsari; Henry J. Snaith; Bruno Ehrler; Richard H. Friend; Felix Deschler

Paper Abstract

We mapped the propagation of photogenerated luminescence and charges from a local photoexcitation spot in thin films of lead tri-iodide perovskites using a confocal microscopy setup with independent excitation and collection objectives. We observed regenerated PL emission at distances as far as 50 micrometers away from photoexcitation. We then made a scratch in the film to increase out-scattering and found that the peak of the internal photon spectrum red-shifts from 765 to ≥800 nanometers. This is caused by the sharp decay of the absorption coefficient at the band tail, which allows longer wavelength photons to travel further between emission and absorption events, originating charges far from excitation. We then built a lateral-contact solar cell with selective electron- and hole-collecting contacts, using a combination of photolitography and electrodeposition. 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. We connect these two observations by comparing the decay in intensity of the recycled component of the PL (which is around 765 nm) with the decay in photocurrent. Taking into account that PL is proportional to the square of charge density, whilst photocurrent is proportional to charge density. Photon recycling leads to an increase in internal photon densities, which leads to a build-up of excited charges. This increases the split of quasi-Fermi levels and enhances the achievable open circuit voltage in a solar cell.

Paper Details

Date Published: 3 November 2016
PDF: 1 pages
Proc. SPIE 9937, Next Generation Technologies for Solar Energy Conversion VII, 99370I (3 November 2016); doi: 10.1117/12.2235237
Show Author Affiliations
Luis Pazos, Univ. of Cambridge (United Kingdom)
Monika Szummilo, Univ. of Cambridge (United Kingdom)
Robin Lamboll, Univ. of Cambridge (United Kingdom)
Johannes M. Richter, Univ. of Cambridge (United Kingdom)
Micaela Crespo-Quesada, Univ. of Cambridge (United Kingdom)
Mojtaba Abdi-Jalebi, Univ. of Cambridge (United Kingdom)
Harry J. Beeson, Univ. of Cambridge (United Kingdom)
Milan Vrucinic, Univ. of Cambridge (United Kingdom)
Mejd Alsari, Univ. of Cambridge (United Kingdom)
Henry J. Snaith, Univ. of Oxford (United Kingdom)
Bruno Ehrler, FOM Institute for Atomic and Molecular Physics (Netherlands)
Richard H. Friend, Univ. of Cambridge (United Kingdom)
Felix Deschler, Univ. of Cambridge (United Kingdom)

Published in SPIE Proceedings Vol. 9937:
Next Generation Technologies for Solar Energy Conversion VII
Oleg V. Sulima; Gavin Conibeer, Editor(s)

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