Title | Impact of self-assembled monolayers as hole transport layers in a mixed MA free Pb/Sn perovskite solar cell
Date | January 8, 2024 @ 09:30
Abstract | Mixed lead (Pb) – tin (Sn) perovskite (PK) solar cells increase rapidly in efficiency lately notably because of improvement of bulk defects and interface passivation. Those devices commonly use poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) as hole transport layer due to its ease of process and good energy level alignment but it also impedes the thermal stability of the device [1]. Here, we use self-assembled monolayer (SAM), [2-(9H-Carbazol-9-yl)ethyl]phosphonic acid (2-PACz) and methylphosphonic acid (MPA) to replace PEDOT:PSS layer. Devices with SAM instead of PEDOT:PSS show poor performances which is opposite to Kapil et al. results obtained with mixed methylammonium (MA) based Pb-Sn perovskite [2]. By using photoluminescence (PL) and ultraviolet photoelectron spectroscopy (UPS), we show that this behaviour is due to a potential barrier created at the interface SAM/MA free PK. But, SAM layers also show less interface non radiative recombination which highlight our interest for those layers. Those results identify 2PACz and MPA effectiveness limits in mixed MA free Pb-Sn perovskite solar cells and give insight for other SAM tests.
[1] R. Prasanna et al., Nature Energy 4, 939 (2019), https://doi.org/10.1038/s41560-019-0471-6.
[2] G. Kapil et al., ACS Energy Lett. 7, 966 (2022), https://doi.org/10.1021/acsenergylett.1c02718
