Multidentate Chelation Achieves Bilateral Passivation toward Efficient and Stable Perovskite Solar Cells with Minimized Energy Losses

Defects in the electron transport layer (ETL), perovskite, and buried interface will result in considerable nonradiative recombination. Here, a bottom-up bilateral modification strategy is proposed by incorporating arsenazo III (AA), a chromogenic agent for metal ions, to regulate SnO2 nanoparticles. AA can complex with uncoordinated Sn4+/Pb2+ in the form of multidentate chelation. Furthermore, by forming a hydrogen bond with formamidinium (FA), AA can suppress FA(+) defects and regulate crystallization. Multiple chemical bonds between AA and functional layers are established, synergistically preventing the agglomeration of SnO2 nanoparticles, enhancing carrier transport dynamics, passivating bilateral defects, releasing tensile stress, and promoting the crystallization of perovskite. Ultimately, the AA-optimized power conversion efficiency (PCE) of the methylammonium-free (MA-free) devices (Rb-0.02(FA(0.95)Cs(0.05))(0.98)PbI2.91Br0.03Cl0.06) is boosted from 20.88% to 23.17% with a high open-circuit voltage (VOC) exceeding 1.18 V and ultralow energy losses down to 0.37 eV. In addition, the optimized devices also exhibit superior stability.

Automated summary

In this study, a bottom-up bilateral modification strategy was proposed to optimize the performance of perovskite solar cells. By incorporating arsenazo III (AA) into SnO2 nanoparticles, defects in the electron transport layer, perovskite, and buried interface could be regulated, resulting in improved stability and energy conversion efficiency of the devices.