Uneven crystallization of lead halide perovskite in the carbon-electrode based, low-temperature mesoscopic perovskite solar cells
Uneven crystallization of lead halide perovskite in the carbon-electrode based, low-temperature mesoscopic perovskite solar cells
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DOI：
10.1063/5.0120065
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发表时间：
2022-11
影响因子：
3.2
通讯作者：
Qing Rong;De'en Guo;Jiao Ma;Si-yuan Lin;Han Huang;Deming Kong;Yongli Gao;Cong-hua Zhou
中科院分区：
文献类型：
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作者：
Qing Rong;De'en Guo;Jiao Ma;Si-yuan Lin;Han Huang;Deming Kong;Yongli Gao;Cong-hua Zhou
在基于碳电极的低温介观钙钛矿太阳能电池中监测钙钛矿的结晶。通过改变碳电极的膜厚或钙钛矿前驱体的体积，研究了钙钛矿的晶体学和形态学性质。观察到，当使用相对薄的碳电极或大体积的钙钛矿前体时，钙钛矿微晶主要形成在器件表面上，留下器件的底部部分未润湿。然而，如果使用较厚的碳电极或较少的钙钛矿前体，则可以在整个多孔骨架中看到结晶，并且实现钙钛矿微晶的相对均匀分布。因此，观察到不均匀的结晶。这种行为是由于表面上的溶剂蒸发，这促进了表面上的成核过程，同时由于奥斯特瓦尔德熟化效应而延迟了底部上的结晶。研究了电荷转移/复合过程和光电转换特性。如所预期的，不均匀结晶导致延迟的电荷转移和增加的复合风险，以及差的功率转换效率，例如，1.3%。相比之下，均匀结晶加速电荷转移并降低复合风险，并将效率提高到高于11%（AM 1.5G，100 mW/cm 2）。
Crystallization of perovskite is monitored in carbon-electrode based, low-temperature, mesoscopic perovskite solar cells. Crystallographic and morphological properties of the perovskite are examined through changes in the film thickness of carbon-electrode or the volume of perovskite precursor. It is observed that, when a relatively thin carbon-electrode or large volume of perovskite precursor is used, perovskite crystallites mainly form on the device surface, leaving the bottom part of the device un-wetted. However, if a thicker carbon-electrode or less perovskite precursor is used, crystallization could be seen in the whole porous skeleton, and relative uniform distribution of perovskite crystallites is achieved. As such, uneven crystallization is observed. Such behavior is due to solvent evaporation on the surface, which facilitates nucleation processes on the surface, while retards crystallization on the bottom due to the Ostwald ripening effect. Charge transfer/recombination processes and photo-to-electric power conversion properties are studied. As expected, uneven crystallization results in retarded charge transfer and increased risk of recombination, and poor power conversion efficiency, for example, ∼3%. In contrast, uniform crystallization accelerates charge transfer and reduces recombination risk, and increases the efficiency to higher than 11% (AM1.5G, 100 mW/cm2).