Wide-bandgap MAPbBr 3 perovskite solar cells using bifunctional-molecule additives achieving a high open-circuit voltage of 1.63 V

Wide-bandgap methyl ammonium lead bromide (MAPbBr 3 ) perovskite solar cells (PSCs) attracts considerable attention due to their large open-circuit voltage ( V OC ), high phase stability and great potential for multi-junction tandem PSCs. However, the low film quality and high defect density of perovskite films limit the development of MAPbBr 3 PSCs. Here, we employ a bifunctional-molecule of 3-chlorbenzylamine additive (3-CBA) to fabricate high quality MAPbBr 3 films in ambient air and facilitate the crystallization of MAPbBr 3 film, leading to higher orientated perovskite film. Additionally, 3-CBA associating with uncoordinated Pb ions effectively passivates the bulk defects, which suppresses the carrier recombination in perovskite films and obtains a high V OC of 1.63 V. To further suppress the carrier recombination at MAPbBr 3 /carbon interface, the 3-CBA is also used to modify the surface of the MAPbBr 3 films. As a result, the 3-CBA modified MAPbBr 3 film exhibits decreased roughness and increased coverage on substrates, which raises the power conversion efficiency (PCE) to 9.55 %. More importantly, the chlorphenyl in 3-CBA for both bulk and surface treatment makes the MAPbBr 3 surface more hydrophobic, which enhances the stability of unencapsulated PCSs allowing it to maintain over 98 % of the initial PCE under 80 degrees C thermal stress and 40 -70 % relative humidity. This work provides a reliable approach to enhance both the V OC and stability for MAPbBr 3 wide-bandgap PSCs.