ACS Appl Mater Interfaces. 2018 Sep 19;10(37):31535-31540. doi: 10.1021/acsami.8b08888. Epub 2018 Sep 7.
Organic-inorganic perovskite solar cells have seen tremendous developments in recent years. As a hole transport material, 2,2',7,7'-tetrakis( N, N-di- p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) is widely used in n-i-p perovskite solar cells. However, it may lead to the perovskite film degradation due to the dopant lithium bis((trifluoromethyl)sulfonyl)amide (Li-TFSI), which has strong hydrophilicity. CuS is considered as a superior p-type transport material, which also has a favorable energy level matching with the highest occupied molecular orbital of Spiro-OMeTAD. Herein, a solution-processed organic-inorganic-integrated hole transport layer was reported, which is composed of the undoped Spiro-OMeTAD and CuS layer. Since there is no Li-TFSI doping, it is extremely conductive to the long-term stability of the solar cells. In the meantime, we proposed a method to adjust the lowest unoccupied molecular orbital (LUMO) of SnO via nitrogen implantation (N:SnO). The LUMO of SnO can be tuned from -4.33 to -3.91 eV, which matches well with the LUMO of CHNHPbI (-3.90 eV), and thus helps to reduce hysteresis. The modified hole and electron transport layers were applied in n-i-p perovskite solar cells, which achieve a maximum power conversion efficiency (PCE) of 17.10 and 96% retention of PCE after 1200 h in air atmosphere without any encapsulation.
有机-无机钙钛矿太阳能电池近年来发展迅速。作为空穴传输材料，2,2',7,7'-四[N,N-二(对甲氧基苯基)氨基]-9,9'-螺二芴（Spiro-OMeTAD）广泛应用于 n-i-p 钙钛矿太阳能电池中。然而，由于掺杂剂双（三氟甲烷磺酰基）亚胺锂（Li-TFSI）具有很强的亲水性，可能导致钙钛矿膜降解。CuS 被认为是一种优越的 p 型传输材料，其能级与 Spiro-OMeTAD 的最高占据分子轨道也非常匹配。在此，报道了一种由未掺杂的 Spiro-OMeTAD 和 CuS 层组成的溶液处理的有机-无机集成空穴传输层。由于没有 Li-TFSI 掺杂，这对太阳能电池的长期稳定性极为有利。同时，我们提出了一种通过氮注入（N：SnO）来调整 SnO 的最低未占据分子轨道（LUMO）的方法。SnO 的 LUMO 可以从-4.33 调整到-3.91 eV，与 CHNHPbI 的 LUMO（-3.90 eV）非常匹配，从而有助于减少滞后现象。改性空穴和电子传输层应用于 n-i-p 钙钛矿太阳能电池，在没有任何封装的情况下，在空气气氛中 1200 小时后，其最大功率转换效率（PCE）达到 17.10%，PCE 保留率为 96%。
