Levine, I.; Al-Ashouri, A.; Musiienko, A.; Hempel, H.; Magomedov, A.; Drevilkauskaite, A.; Getautis, V.; Menzel, D.; Hinrichs, K.; Unold, T.; Albrecht, S.; Dittrich, T.: Charge transfer rates and electron trapping at buried interfaces of perovskite solar cells. Joule 5 (2021), p. in press
10.1016/j.joule.2021.07.016
Open Accesn Version

Abstract:
Identification of electronic processes at buried interfaces of charge-selective contacts is crucial for photovoltaic and photocatalysis research. Here, transient surface photovoltage (SPV) is used to study the passivation of different hole-selective carbazole-based SAMs. It is shown that transient SPV and transient photoluminescence provide complementary information on charge transfer kinetics and trapping/de-trapping mechanisms, and that trap-assisted non-radiative recombination losses originate from electron trapping at the SAM-modified ITO/perovskite interface. The hole transfer rates and the density of interface electron traps, obtained by fitting SPV transients with a minimalistic kinetic model, depended strongly on the SAM’s chemical structure, and densities of interface traps as low as 109 cm−2, on par with highly passivated c-Si surfaces, were reached for Me-4PACz, previously used in record perovskite/silicon tandem solar cells. The extracted hole transfer rate constants and interface trap densities correlated well with the corresponding fill factors and open-circuit voltages of high-efficiency solar cells.