Optimal alignment of the energy levels can improve the performance of perovskite solar cells. In this work, we show that energy level alignment can be enhanced by a vacuum-deposited zinc iodide (ZnI₂) layer inserted between tin perovskite and a C₆₀ electron transport layer. The open-circuit voltage of FA_0.75MA_0.25SnI₃ (FA: formamidinium; MA: methylammonium) solar cells increased by more than 0.1 V, while the power conversion efficiency increased from 10.2% to 12.8%. The shelf lifetimes of the devices are also improved. ZnI₂ interlayers are also effective with other perovskites compositions, such as FASnI₃ and PEA_0.15FA_0.85SnI₃ (PEA: phenethylammonium), with their device efficiencies increasing from 6.8% to 11.6% and from 6.2% to 9.5%, respectively. The energy level diagram, derived from Kelvin probe measurements, suggests that ZnI₂ interlayers reduce the band offset between perovskite and C₆₀. As a result, the electron accumulation width in C₆₀ is reduced, mitigating nonradiative charge carrier recombination losses and increasing the device performance.

中文翻译：

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提高含碘化锌中间层的卤化锡钙钛矿太阳能电池的功率转换效率


能量水平的最佳对齐可以提高钙钛矿太阳能电池的性能。在这项工作中，我们表明，通过在锡钙钛矿和 C₆₀ 电子传递层之间插入真空沉积的碘化锌 （ZnI₂） 层可以增强能级对齐。开路电压 FA_0.75MA_0.25SnI₃ （FA： 甲脒;MA：甲基铵）太阳能电池增加了 0.1 V 以上，而功率转换效率从 10.2% 提高到 12.8%。设备的保质期也得到了延长。ZnI₂ 中间层也与其他钙钛矿成分有效，例如 FASnI₃ 和 PEA_0.15FA_0.85SnI₃（PEA：苯乙基铵），它们的器件效率分别从 6.8% 提高到 11.6% 和 6.2% 到 9.5%。从开尔文探针测量得出的能级图表明，ZnI₂ 夹层减少了钙钛矿和 C₆₀ 之间的能带偏移。因此，C₆₀ 中的电子积累宽度减小，减轻了非辐射电荷载流子复合损耗并提高了器件性能。