Controllable Heavy n–type Behaviours in Inverted Perovskite Solar Cells with Non‐Conjugated Passivants

Interfacial issues between the perovskite film and electron transport layer greatly limit the efficiency and stability of inverted (p-i-n) perovskite solar cells (PSCs). Despite organic ammonium passivants have been widely established as interfacial layers, they failed to improve electron extraction. Here, we reported that the heavy n-type characteristics in a low band gap perovskite film could be modulated by incorporating non-conjugated ammonium passivants with strong electron-withdrawing abilities. This resulted in a significant enhancement of electron extraction in the heavily n-type doped perovskite. The passivant-treated PSCs exhibited a power conversion efficiency of 25.74 % with an excellent fill factor of 85.4 % and a high open-circuit voltage of 1.166 V, which are significantly higher than that of the control device. The unencapsulated devices maintained 88 % of their initial PCEs after 1,200 hours at 85 °C.