In the planar perovskite solar cells (PSCs), the electron transport layer (ETL) plays a critical role in electron extraction and transport. Widely utilized TiO₂ ETLs suffer from the low conductivity and high surface defect density. To address these problems, for the first time, two types of ETLs based on TiO₂ phase junction are designed and fabricated distributed in the opposite space, namely anatase/rutile and rutile/anatase. The champion efficiency of PSCs based on phase junction ETL is over 15%, which is much higher than that of cells with single anatase (9.8%) and rutile (11.8%) TiO₂ as ETL. The phase junction based PSCs also demonstrated obviously reduced hysteresis. The enhanced performance is discussed and mainly ascribed to the excellent capability of carrier extraction, defect passivation, and reduced recombination at the ETL/perovskite interface. This work opens a new phase junction ETL strategy toward interfacial energy band manipulation for improved PSC performance.

中文翻译：

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TiO2 相结电子传输层提高平面钙钛矿太阳能电池的效率

在平面钙钛矿太阳能电池（PSC）中，电子传输层（ETL）在电子提取和传输中起着至关重要的作用。广泛使用的TiO ₂ ETL 存在电导率低和表面缺陷密度高的问题。为了解决这些问题，首次设计并制造了两种分布在相反空间的基于TiO _{2相结的ETL，即锐钛矿/金红石和金红石/锐钛矿。}基于相结ETL的PSC的冠军效率超过15%，远高于使用单一锐钛矿（9.8%）和金红石（11.8%）TiO ₂作为ETL的电池的冠军效率。基于相结的 PSC 还表现出明显减少的滞后。讨论了性能的增强，主要归因于 ETL/钙钛矿界面优异的载流子提取、缺陷钝化和减少复合能力。这项工作开辟了一种新的相结 ETL 策略，旨在通过界面能带操纵来提高 PSC 性能。