Perovskite Solar Cells with an SbX3 (X = Cl, I) Interface Dipole Layer

Forming an interface dipole moment pointing from the absorber to the oxide substrate can improve the open-circuit voltage (VOC) of perovskite solar cells (PSCs) without affecting photocurrent. In past studies, however, interface dipole layers were generally formed using organic self-assembled monolayers or polyelectrolytes, which raises concerns about intrinsic stability. Meanwhile, perovskites’ substrate-dependent electronic properties question the apparent correlation between the oxide’s work function and the built-in voltage. In this work, we propose an interface dipole layer based on solution-processable metal halides, which increases the built-in voltage of the n–i–p diode by simultaneously reducing the electron transport layer’s work function and strengthening the n-type characteristics of the perovskite absorber. The n–i–p-structured PSCs with the SbX3 dipole layer achieve substantially enhanced VOC (1.171 V) and power conversion efficiency (23.11%). Further experiments and calculations confirm that the proposed dipole model can explain the VOC enhancement qualitatively and quantitatively.