Enhanced device performance and stability of perovskite solar cells with low-temperature ZnO/TiO2 bilayered electron transport layers

Caifeng Zhang; Guangmei Zhai; Yong Zhang; Wenhui Gao; Zhimeng Shao; Lulu Zheng; Fuhong Mei; Hua Zhang; Yongzhen Yang; Xuemin Li; Xuguang Liu; Bingshe Xu

doi:10.1039/c8ra03162b

Enhanced device performance and stability of perovskite solar cells with low-temperature ZnO/TiO₂ bilayered electron transport layers

RSC Adv. 2018 Jun 22;8(41):23019-23026. doi: 10.1039/c8ra03162b. eCollection 2018 Jun 21.

Authors

Caifeng Zhang^{1

2

3}, Guangmei Zhai^{1

2

3}, Yong Zhang^{1

3

4}, Wenhui Gao^{1

3}, Zhimeng Shao^{1

3}, Lulu Zheng^{1

3}, Fuhong Mei^{1

3}, Hua Zhang^{1

3}, Yongzhen Yang^{1

3}, Xuemin Li^{1

3}, Xuguang Liu^{1

3

4}, Bingshe Xu^{1

3}

Affiliations

¹ Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education, Research Centre of Advanced Materials Science and Technology, Taiyuan University of Technology Taiyuan Shanxi 030024 China [email protected] [email protected].
² CAS Key Laboratory of Renewable Energy Guangzhou 510640 China.
³ Collaborative Innovation Centre for Advanced Thin-film Optoelectronic Materials and Devices in Shanxi Province Taiyuan Shanxi 030024 China.
⁴ College of Materials Science and Engineering, Taiyuan University of Technology Taiyuan Shanxi 030024 China.

Abstract

The instability of perovskite films is a major issue for perovskite solar cells based on ZnO electron transport layers (ETLs). Here, ZnO nanoparticle (NP)- and ZnO sol-gel layers capped with low-temperature processed TiO₂, namely ZnO/TiO₂ bilayered films, have been successfully employed as ETLs in highly efficient MAPbI₃-based perovskite solar cells. It is demonstrated that these ZnO/TiO₂ bilayered ETLs are not only capable of enhancing photovoltaic performance, but also capable of improving device stability. The best device based on the ZnO/TiO₂ bilayered ETL exhibits an efficiency of ∼15% under standard test conditions and can retain nearly 100% of its initial efficiency after 30 days of atmosphere storage, showing much higher device performance and stability compared to those devices based on ZnO single-layer ETLs. Moreover, it is found that perovskite films and devices prepared on the single ZnO sol-gel ETLs are much superior to those deposited on the single ZnO NP-ETLs in both stability and performance, which can be ascribed to fewer surface hydroxyl groups and much smoother surface morphology of the ZnO sol-gel films. The results pave the way for ZnO to be used as an effective ETL of low-temperature processed, efficient and stable PSCs compatible with flexible substrates.