Origins of the Accelerated Decomposition in Inorganic Tin Perovskites Contaminated by Oxygen: Ab Initio and Quantum Dynamics Study

作者：Li, Akang; Liu, Qi; Liang, WanZhen^*

来源：Journal of Physical Chemistry C, 2023.

DOI：10.1021/acs.jpcc.3c04066

• SOLAR-CELLS
• HALIDE PEROVSKITES
• MOLECULAR-DYNAMICS
• CSSNI3 PEROVSKITE
• PYXAID PROGRAM
• LEAD
• DEGRADATION
• STABILITY
• SUBSTITUTION
• PERFORMANCE

Tin-based perovskites are one of the most promising candidatesfor the development of lead-free perovskite solar cells (PSCs) andhave attracted lots of attention. Despite the extensive research efforts,the performance of tin-based PSCs (Sn-PSCs) still lags far behindthe lead containing counterparts due to the poor stability and self-p-doping.Here, we perform first-principles density functional theory calculationscombined with non-adiabatic molecular dynamics simulations to unveilthe origins of the instability of tin iodine perovskite when exposedto O-2. It is found that O-2 is more thermallyfavorable to be adsorbed on iodine-vacancy (V-I) defectsites in the defective surface rather than the pristine surface, andthe generation of peroxide species on the V-I sites dramaticallyaccelerates the structural decomposition. The presence of V-I defects on the surface of CsSnI3 decreases the band gapby inducing a local shallow state around conduction band minimum,significantly accelerating the electron-hole recombination.The adsorption of O-2 on V-I site slightly increasesthe band gap compared to that of the pristine one and decreases theinfluence of V-I on the surface's optoelectronicproperties and the electron-hole recombination rate but significantlyaccelerates structural decomposition by weakening the defect toleranceability of the [SnI6](4-) octahedra aswell as the carriers' relaxation. The increased structuralinstability in combined V-I and O-2 points tothe surface V-I defect passivation as the main optimizationscheme for efficient and stable Sn-PSCs.

• 单位
  厦门大学