Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
Publication date: 20th April 2022
Perovskite solar cells rely on selective transport layers to efficiently extract charge carriers and reduce non-radiative recombination at the interface to the contacts. Although the bulk materials are relatively well understood, non-radiative recombination of charge carriers at the interfaces between the perovskite and the charge selective transport layers is still not fully understood nor eliminated, causing a drop in the open circuit voltage and therefore device efficiency. Usually, partial cell stacks are used to resolve the different interfaces and study the non-radiative recombination with photoluminescence (PL) techniques. However, this does not allow for study of non-radiative recombination at a contact under operating conditions with electrical bias.
In this work, interdigitated-back-contact cells are made such that the optical properties of the perovskite-nickel oxide interfaces can be studied in operando. Because the contacts are placed in plane, instead of stacked vertically, we can probe the optical properties in a spatially resolved manner from the top. We study the recombination dynamics of charge carriers with steady-state PL and transient PL, both under electrical bias. These measurements suggest the presence of a extraction barrier that decreases with the application of an increasing bias voltage. The timescale of the dynamics of the extraction barrier indicates that ions play a key role in the extraction of carriers at the nickel oxide contacts.