Improving the performance of perovskite solar cells by surface passivation

NiO has a perfect-aligned energy level with CH3 NH3 Pb I3 perovskite such that it serves as a hole transport layer(HTL), but Ni O-based perovskite solar cells(PSCs) still suffer from low efficiency due to the poor interface contact between the perovskite layer and the Ni O HTL, and haphazardly stacked perovskite grains.Herein, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1,3}-thiadiazole)](PFBT) is introduced between the Ni O and perovskite layers in the form of a polymer aggregate to enhance perovskite crystallinity and decrease the interface charge recombination between perovskite and Ni O in PSCs, resulting in an improved performance. Moreover, PFBT modified perovskite films showed sharper, smoother, and more compact crystalline grains with fewer grain boundaries, leading to the decreased nonradiative recombination. This study offers a simple strategy to achieve highly efficient PSCs with the incorporation of polymer semiconductor aggregates to passivate the interface between the perovskite and Ni O layers.