Hannes Hempel - Transient Photoluminescence of Lead Halide Perovskites Beyond Lifetimes

Relevant papers:
https://doi.org/10.1002/aenm.202102776
https://doi.org/10.1103/PhysRevApplie...

For more information about the NGSE PhD-Postdoc series and to register for future talks go to:
https://www.ngse.info/phd-postdoc-ser...

Follow us on Twitter at:
  / ngse_conf  
  / imeet_pv  

Talk Given by Hannes Hempel on the 13th of March 2024

Abstract:
Transient photoluminescence (trPL) is the standard technique to quantify the lifetimes of photogenerated charge carriers in energy conversion materials. However, trPL decays are sensitive to processes other than only carrier recombination. We show that the initial trPL transients of lead halide perovskite thin films on glass are dominated by charge transport, namely hot carrier transport, spread-out of non-excitonic gemmate pairs, and redistribution. Including these processes in the modeling of trPL yields the doping and intrinsic carrier concentration, the mobility and diffusion coefficient, the hot carrier transport length, and the radiative and non-radiative lifetimes. Further, we calibrate trPL to absolute photon numbers, which allows quantifying the transient quasi-Fermi-level splitting and reveals fundamental energy losses in photo absorbers such as the increase of entropy by loss of geminate correlation and redistribution. The presented analysis is crucial for the appropriate interpretation of trPL and yields almost all optoelectronic properties relevant for application as a photo-absorber in solar cells.