Effect of TiO2:Zn layer thickness on the performance of MAPbI3-based perovskite solar cells fabricated under open-air condition

Abstract

In this research, we study the effect of the layer thickness of 2 % mol Zn doped-TiO₂ layers on MAPbI₃-based perovskite solar cells (PSCs) performance. MAPbI₃-based PCSs have low efficiency. One of the limiters of the MAPbI₃-based PSC’s efficiency is the thickness of TiO₂ and its electrical properties. This research aims to enhance MAPbI₃-based PSC efficiency by optimizing the thickness of the Zn-doped TiO₂ layer used as the electron transport layer (ETL). The samples were prepared by depositing Zn-doped TiO₂ onto indium tin oxide (ITO) glass substrates using a spin coating technique, resulting in samples with 1 (S1), 3 (S2), 5 (S3), and 7 (S4) times of coating and with the structure ITO/TiO₂:Zn/MAPbI₃/graphite/ITO. I-V electrical testing revealed increased MAPbI₃-based PSC efficiency from 11.33 % to 11.54 %, 12.46 %, and 12.97 % for 1, 3, 5, and 7 times of coating, respectively. X-ray diffraction measurements indicated a tetragonal crystal structure with an increase in crystallite size from 17.92 nm to 18.85, 19.73, 20.67 nm for 1, 3, 5, and 7 times of coating, respectively. Scanning electron microscope (SEM) on surface section confirmed that the particle size of each sample is 17.84, 25.23, 28.3, and 30.90 nm for 1, 3, 5, and 7 times of coating, respectively. Based on SEM on cross-sectional, the thickness of each sample is 346, 466, 569, and 695 nm, for 1, 3, 5, and 7 times of coating, respectively. UV–VIS spectroscopy analysis a decrease in the band gap from 3.3 eV to 3.25 eV, 3.2 eV, and 3.15 eV for 1, 3, 5, and 7 times of coating, respectively. These findings highlight the potential for improving MAPbI₃-based PSC efficiency by optimizing Zn-doped TiO₂ layer thickness, with significant implications for MAPbI₃-based PSC fabrication in open-air environments.