posted on 2021-12-28, 16:06authored byXuehao Zhang, Yang Hao, Shiqi Li, Jingkun Ren, Yukun Wu, Qinjun Sun, Yanxia Cui, Yuying Hao
Low-bandgap
tin–lead mixed perovskites (PVKs) are necessary
for all-perovskite tandem solar cells. This work proposes a multifunctional
sandwich structure with 2-chloroethylamine (CEA) as the top and bottom
interface layer and perovskite as the core layer. The sandwich structured
CEA allows large ClCH2CH2NH3+ and small Cl– to diffuse into the crystal
lattice and grain boundaries of perovskites, endowing an excellent
antioxidation property by forming Sn(0), coordinating with SnI2, and controlling the perovskite crystallization process.
Moreover, the energy level alignment at the interface of the perovskite
and transport layer becomes more matched. As a result, the CEA-modified
champion device acquires a power conversion efficiency of 18.13% with
an open-circuit voltage of 0.82 V and a short-circuit current density
of 30.06 mA cm–2. Meanwhile, the environmental stability
of CEA-modified devices is substantially enhanced. This work introduces
a new strategy for improving the performance and stability of tin–lead
mixed perovskite solar cells.