Effect of Surface Ligand on Charge Separation and Recombination at CsPbI 3 Perovskite Quantum Dot/TiO 2 Interfaces
Effect of Surface Ligand on Charge Separation and Recombination at CsPbI 3 Perovskite Quantum Dot/TiO 2 Interfaces
复制标题
表面配体对CsPbI 3 钙钛矿量子点/TiO 2 界面电荷分离和复合的影响
DOI：
10.1021/acs.jpcc.9b06725
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Lian, Tianquan
中科院分区：
文献类型：
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作者：
Shang, Qiongyi;Piercy, Brandon D.;Losego, Mark D.;Lian, Tianquan
CsPbI3钙钛矿量子点（QD）太阳能电池由于与散装材料相比具有更高的稳定性，因此成为有前景的进一步开发设备平台。这些装置的制造通常涉及胶体量子点的合成后清洗以去除表面配体。在此，我们研究了这种后合成处理如何影响 CsPbI3QD 和 TiO2 电子提取层界面处的电荷分离 (CS) 和电荷复合 (CR) 过程。 QD/TiO2 界面处的 CS 时间常数从直接沉积在 TiO2 上的 QD 的 457 ± 4 ps 降低到用乙酸甲酯洗涤两次的 QD 的 288 ± 1 ps，从而将 ET 效率从 89.9 ± 0.3% 提高到 98.3 ± 0.01%。有趣的是，这种处理还将平均电荷复合时间常数从346±18ns延长到1180±60ns，这也有利于减少电荷复合损失。这一结果证明了醋酸甲酯（MeOAc）洗涤量子点对界面电荷转移过程的显着影响，表明胶体钙钛矿量子点的合成后修饰对太阳能电池效率的重要影响。
CsPbI3perovskite quantum dot (QD) solar cells are a promising device platform for further development due to their improved stability compared to bulk materials. The fabrication of these devices often involves postsynthetic washing of colloidal QDs to remove surface ligands. Herein, we investigate how this postsynthetic treatment affects the charge separation (CS) and charge recombination (CR) processes at the interface of CsPbI3QDs and the TiO2electron extraction layer. The CS time constant at QD/TiO2interface decrease from 457 ± 4 ps for QDs directly deposited on TiO2to 288 ± 1 ps for QDs that were washed twice by methyl acetate, increasing the ET efficiency from 89.9 ± 0.3% to 98.3 ± 0.01%. Interestingly, this treatment also lengthens the average charge recombination time constants from 346 ± 18 ns to 1180 ± 60 ns, which is also beneficial for reducing charge recombination loss. This result demonstrates the pronounced effect of QD washing by methyl acetate (MeOAc) on interfacial charge transfer processes, suggesting the important effect of postsynthesis modification of colloidal perovskite QDs on solar cell efficiencies.