TiO2 Phase Junction Electron Transport Layer Boosts Efficiency of Planar Perovskite Solar Cells

Yayun Zhu; Kaimo Deng; Haoxuan Sun; Bangkai Gu; Hao Lu; Fengren Cao; Jie Xiong; Liang Li

doi:10.1002/advs.201700614

TiO₂ Phase Junction Electron Transport Layer Boosts Efficiency of Planar Perovskite Solar Cells

Adv Sci (Weinh). 2018 Jan 6;5(3):1700614. doi: 10.1002/advs.201700614. eCollection 2018 Mar.

Authors

Yayun Zhu¹, Kaimo Deng¹, Haoxuan Sun², Bangkai Gu¹, Hao Lu¹, Fengren Cao¹, Jie Xiong², Liang Li¹

Affiliations

¹ College of Physics, Optoelectronics and Energy Jiangsu Key Laboratory of Thin Films Center for Energy Conversion Materials & Physics (CECMP) Soochow University Suzhou 215006 P. R. China.
² State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China Chengdu 610054 P. R. China.

Abstract

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.

Keywords: atomic layer deposition; electron transport layers; perovskites; phase junctions; titanium oxide.