Efficient inverted perovskite solar cells using phosphonic acid additive modification

Defect passivation in perovskite semiconductors remains challenging but essential for enhancing the efficiency and long-term stability of perovskite solar cells (PSCs). Additives engineering has been identified as an effective approach due to their in-situ passivation of grain boundaries and defects during film formation. Herein, we introduced a phosphonic acid-based molecule [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) as an additive to enhance the performance of inverted methylammonium lead triiodide (MAPbI3) PSCs. It is found that the addition of MeO-2PACz not only modifies the crystallization of MAPbI3 film with more uniform grain size, but also effectively passivates defects, resulting in a reduction of trap-state density and suppressed charge recombination losses within MAPbI3 perovskites. As a result, an improved champion efficiency of 15.45% with an apparent rise in Voc and Jsc was achieved for MeO-2PACz treated inverted MAPbI3 device, compared with the 10.20% efficiency of the control device. This work demonstrates that the selection of phosphonic acid molecules as additives and passivators can substantially enhance the performance of PSCs.