Wu Wu-Qiang, Rudd Peter N, Ni Zhenyi, Van Brackle Charles Henry, Wei Haotong, Wang Qi, Ecker Benjamin R, Gao Yongli, Huang Jinsong
Department of Applied Physical Sciences , University of North Carolina , Chapel Hill , North Carolina 27599 , United States.
Nanomaterials Centre, School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology , The University of Queensland , Brisbane , QLD 4072 , Australia.
J Am Chem Soc. 2020 Feb 26;142(8):3989-3996. doi: 10.1021/jacs.9b13418. Epub 2020 Feb 17.
State-of-the-art, high-performance perovskite solar cells (PSCs) contain a large amount of iodine to realize smaller bandgaps. However, the presence of numerous iodine vacancies at the surface of the film formed by their evaporation during the thermal annealing process has been broadly shown to induce deep-level defects, incur nonradiative charge recombination, and induce photocurrent hysteresis, all of which limit the efficiency and stability of PSCs. In this work, modifying the defective surface of perovskite films with cadmium iodide (CdI) effectively reduces the degree of surface iodine deficiency and stabilizes iodine ions via the formation of strong Cd-I ionic bonds. This largely reduces the interfacial charge recombination loss, yielding a high efficiency of 21.9% for blade-coated PSCs with an open-circuit voltage of 1.20 V, corresponding to a record small voltage deficit of 0.31 V. The CdI surface treatment also improves the operational stability of the PSCs, retaining 92% efficiency after constant illumination at 1 sun intensity for 1000 h. This work provides a promising strategy to optimize the surface/interface optoelectronic properties of perovskites for more efficient and stable solar cells and other optoelectronic devices.
最先进的高性能钙钛矿太阳能电池（PSC）含有大量碘以实现更小的带隙。然而，在热退火过程中通过蒸发形成的薄膜表面存在大量碘空位，这已被广泛证明会诱导深能级缺陷、引发非辐射电荷复合并导致光电流滞后，所有这些都会限制PSC的效率和稳定性。在这项工作中，用碘化镉（CdI）修饰钙钛矿薄膜的缺陷表面有效地降低了表面碘缺乏程度，并通过形成强Cd-I离子键来稳定碘离子。这在很大程度上减少了界面电荷复合损失，对于刀片涂覆的PSC，开路电压为1.20 V，效率高达21.9%，对应于创纪录的0.31 V小电压亏缺。CdI表面处理还提高了PSC的运行稳定性，在1个太阳强度下持续光照1000小时后仍保持92%的效率。这项工作为优化钙钛矿的表面/界面光电特性以制造更高效、稳定的太阳能电池和其他光电器件提供了一种有前景的策略。
