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Fast Crystallization and Improved Stability of Perovskite Solar Cells with Zn2SnO4 Electron Transporting Layer: Interface Matters

Bera, Ashok, Sheikh, Arif D., Haque, Md. Azimul, Bose, Riya, Alarousu, Erkki, Mohammed, Omar F., Wu, Tom
ACS Applied Materials & Interfaces 2015 v.7 no.51 pp. 28404-28411
absorption, coatings, crystallization, encapsulation, energy conversion, hysteresis, photovoltaic cells, porous media, solvents, titanium dioxide
Here we report that mesoporous ternary oxide Zn₂SnO₄ can significantly promotes the crystallization of hybrid perovskite layers and serves as an efficient electron transporting material in perovskite solar cells. Such devices exhibit an energy conversion efficiency of 13.34%, which is even higher than that achieved with the commonly used TiO₂ in the similar experimental conditions (9.1%). Simple one-step spin coating of CH₃NH₃PbI₃–ₓClₓ on Zn₂SnO₄ is found to lead to rapidly crystallized bilayer perovskite structure without any solvent engineering. Furthermore, ultrafast transient absorption measurement reveals efficient charge transfer at the Zn₂SnO₄/perovskite interface. Most importantly, solar cells with Zn₂SnO₄ as the electron-transporting material exhibit negligible electrical hysteresis and exceptionally high stability without encapsulation for over one month. Besides underscoring Zn₂SnO₄ as a highly promising electron transporting material for perovskite solar cells, our results demonstrate the significant role of interfaces on improving the perovskite crystallization and photovoltaic performance.