Fundamental Flaw in the Current Construction of the TiO2 Electron Transport Layer of Perovskite Solar Cells and Its Elimination
Fundamental Flaw in the Current Construction of the TiO2 Electron Transport Layer of Perovskite Solar Cells and Its Elimination
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钙钛矿太阳能电池TiO2电子传输层现有结构的根本缺陷及其消除
DOI：
10.1021/acsami.1c09742
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发表时间：
2021
影响因子：
9.5
通讯作者：
Zhao Jincai
中科院分区：
文献类型：
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作者：
Yan Yan;Liu Cheng;Yang Yi;Hu Guoxiang;Tiwari V;ana;Jiang De-en;Peng Wei;Jha Ajay;Duan Hong-Guang;Tellkamp Friedjof;Ding Yong;Shi Weidong;Yuan Shouqi;Miller Dwayne;Ma Wanhong;Zhao Jincai
性能最好的钙钛矿太阳能电池（效率> 20%）通常依赖于使用TiO 2电子传输层（ETL）。然而，目前使用市售TiO 2纳米糊剂的立体定向制备的TiO 2 ETL的功效和稳定性远未达到其最大值。如本文所揭示的，这种差异的长期隐藏的原因是由于有机质子溶剂（主要是醇）的分解，酸性质子（约0.11重量%）在高温烧结后总是保留在TiO 2 ETL中。这些质子容易导致光照射后形成的Ti-H物种，其作用是阻止在钙钛矿/TiO 2界面的电子转移。面对这一挑战，我们引入了一个简单的去质子化方案，通过添加少量的强质子受体（乙醇钠或NaOH）到普通的TiO 2陶瓷浆料前体和复制的高温烧结过程中，这消除了几乎所有的质子在TiO 2 ETL在烧结过程中。使用去质子化的TiO 2 ETL不仅促进了MAPbI 3基和FA0.85MA0.15PbI2.55Br0.45基器件的PCE超过20%，而且还显著提高了目标器件在连续运行1000 h后的长期光稳定性。
The top-performing perovskite solar cells (efficiency > 20%) generally rely on the use of a nanocrystal TiO2electron transport layer (ETL). However, the efficacies and stability of the current stereotypically prepared TiO2ETLs employing commercially available TiO2nanocrystal paste are far from their maximum values. As revealed herein, the long-hidden reason for this discrepancy is that acidic protons (∼0.11 wt %) always remain in TiO2ETLs after high-temperature sintering due to the decomposition of the organic proton solvent (mostly alcohol). These protons readily lead to the formation of Ti–H species upon light irradiation, which act to block the electron transfer at the perovskite/TiO2interface. Affront this challenge, we introduced a simple deprotonation protocol by adding a small amount of strong proton acceptors (sodium ethoxide or NaOH) into the common TiO2nanocrystal paste precursor and replicated the high-temperature sintering process, which wiped out nearly all protons in TiO2ETLs during the sintering process. The use of deprotonated TiO2ETLs not only promotes the PCE of both MAPbI3-based and FA0.85MA0.15PbI2.55Br0.45-based devices over 20% but also significantly improves the long-term photostability of the target devices upon 1000 h of continuous operation.