High Open-Circuit Voltage in Wide-Bandgap Perovskite Photovoltaics with Passivation Layers Based on Large Cations

In this work, passivation interlayers are investigated that enable high open-circuit voltage (V
_OC
) in wide-bandgap perovskite (WBP) solar cells. The interlayers are fabricated by processing a thin film of a large cation precursor on top of a 3D WBP thin-film (E
_G
~ 1.72 eV). The large cations n-butylammonium bromide (BABr) and ethylammonium bromide (EABr) show promising performance in WBP solar cells with stable power output conversion efficiencies of up to 19.4% and 17.9%, respectively. The corresponding V
_OC
of these devices reaches values up to 1.31 V and 1.27 V for BABr and EABr, respectively. Compared to the reference devices without passivation interlayer (V
_OC
~ 1.23 V), this corresponds to an improvement in V
_OC
of up to around 80 meV (BABr) and 40 meV (EABr), respectively. This enhancement in V
_OC
originates from a reduction in non-radiative recombination losses. For the case of BABr, we reported already in a previous publication that a hybrid 2D/3D perovskite heterostructures is formed. Building on these results, in this proceeding paper we compare the performance of WBP solar cells using the large cation BABr and EABr for the processing of a passivation interlayers.