Rutile TiO₂ (R-TiO₂) produced by chemical bath deposition (CBD) is widely considered as the desired electron transport layer (ETL) for perovskite solar cells (PSCs). However, the understanding of the growth mechanism of R-TiO₂ ETL and its general regular pattern affecting power conversion efficiency (PCE) is underappreciated. Herein, the growth mechanism of TiO₂ on fluorine-doped SnO₂ substrate (FTO) is demonstrated and it is revealed that pure R-TiO₂, rather than a rutile/anatase mixed crystal, is formed under an Sn–Ti isostructural substitution effect. The similarity of lattice parameters and phase structure between FTO and R-TiO₂ can reduce interface misfit and nucleation barrier, thus boosting heterogeneous nucleation and growth of R-TiO₂ simultaneously. Based on the key growth conditions of the R-TiO₂ ETL, the dominant distribution of PCE for hole transport layer (HTL)-free carbon-based planar perovskite solar cells is illustrated and discussed, and a champion efficiency of 14.0% is achieved.

中文翻译：

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金红石TiO2电子传输层的同构取代诱导生长机制和高效碳基钙钛矿太阳能电池的主导分布

通过化学浴沉积 (CBD) 生产的金红石 TiO ₂ (R-TiO ₂ ) 被广泛认为是钙钛矿太阳能电池 (PSC) 所需的电子传输层 (ETL)。然而，人们对 R-TiO ₂ ETL的生长机制及其影响功率转换效率 (PCE) 的一般规律的理解未被充分认识。在此，证明了 TiO ₂在掺氟 SnO ₂衬底 (FTO)上的生长机制，并表明在 Sn-Ti 同构取代作用下形成纯 R-TiO ₂，而不是金红石/锐钛矿混晶. FTO和R-TiO ₂晶格参数和相结构的相似性可以减少界面失配和成核势垒，从而同时促进R-TiO _{2 的}异质成核和生长。基于R-TiO ₂ ETL的关键生长条件，阐述和讨论了无空穴传输层（HTL）碳基平面钙钛矿太阳能电池的PCE的主要分布，并实现了14.0%的冠军效率。