Laser-Assisted Ultrafast Fabrication of Crystalline Ta-Doped TiO2 for High-Humidity-Processed Perovskite Solar Cells

Hongbo Mo; Dong Wang; Qian Chen; Wei Guo; Suresh Maniyarasu; Andrew G Thomas; Richard J Curry; Lin Li; Zhu Liu

doi:10.1021/acsami.1c24225

Laser-Assisted Ultrafast Fabrication of Crystalline Ta-Doped TiO₂ for High-Humidity-Processed Perovskite Solar Cells

ACS Appl Mater Interfaces. 2022 Apr 6;14(13):15141-15153. doi: 10.1021/acsami.1c24225. Epub 2022 Mar 24.

Authors

Hongbo Mo^{1

2}, Dong Wang¹, Qian Chen^{1

2}, Wei Guo², Suresh Maniyarasu³, Andrew G Thomas^{1

4

5}, Richard J Curry^{4

5}, Lin Li², Zhu Liu^{1

2}

Affiliations

¹ Department of Materials, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
² Laser Processing Research Center, Department of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
³ Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
⁴ Photon Science Institute, Department of Electrical and Electronic Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.
⁵ Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.

Abstract

A titanium dioxide (TiO₂) compact film is a widely used electron transport layer (ETL) for n-i-p planar perovskite solar cells (PSCs). However, TiO₂ sufferers from poor electrical conductivity, leading to high energy loss at the perovskite/ETL/transparent conductive oxide interface. Doping the TiO₂ film with alkali- and transition-metal elements is an effective way to improve its electrical conductivity. The conventional method to prepare these metal-doped TiO₂ films commonly requires time-consuming furnace treatments at 450-600 °C for 30 min to 3 h. Herein, a rapid one-step laser treatment is developed to enable doping of tantalum (Ta) in TiO₂ (Ta-TiO₂) and to simultaneously induce the crystallization of TiO₂ films from its amorphous precursor to an anatase phase. The PSCs based on the Ta-TiO₂ films treated with the optimized fiber laser (1070 nm) processing parameters (21 s with a peak processing temperature of 800-850 °C) show enhanced photovoltaic performance in comparison to that of the device fabricated using furnace-treated films at 500 °C for 30 min. The ambient-processed planar PSCs fabricated under high relative humidity (RH) of 50-70% display power conversion efficiencies (PCEs) of 18.34% and 16.04% for devices based on Cs_0.1FA_0.9PbI₃ and CH₃NH₃PbI₃ absorbers, respectively. These results are due to the improved physical and chemical properties of the Ta-TiO₂ films treated by the optimal laser process in comparison to those for the furnace process. The laser process is rapid, simple, and potentially scalable to produce metal-doped TiO₂ films for efficient PSCs.

Keywords: Ta-doped TiO2; ambient-processed; laser-assisted doping; perovskite solar cells.