Tin Oxide Modified Titanium Dioxide as Electron Transport Layer in Formamidinium-Rich Perovskite Solar Cells

Abstract

The design of electron transport layers (ETLs) with good optoelectronic properties is one of the keys to the improvement of the power conversion efficiencies (PCEs) and stability of perovskite solar cells (PSCs). Titanium dioxide (TiO2), one of the most widely used ETL in PSCs, is characterized by low electrical conductivity that increases the series resistance of PSCs, thus limiting their PCEs. In this work, we incorporated tin oxide (SnO2) into titanium dioxide (TiO2) and studied the evolution of its microstructural and optoelectronic properties with SnO2 loading. The thin films were then integrated as ETLs in a regular planar Formamidinium (FA)-rich mixed lead halide PSCs so as to assess the overall effect of SnO2 incorporation on their charge transport and Photovoltaic (PV) characteristics. Analysis of the fabricated PSCs devices revealed that the best performing devices; based on the ETL modified with 0.2 proportion of SnO2; had an average PCE of 17.35 ± 1.39%, which was about 7.16% higher than those with pristine TiO2 as ETL. The improvement in the PCE of the PSC devices with 0.2 SnO2 content in the ETL was attributed to the improved electron extraction and transport ability as revealed by the Time Resolved Photoluminescence (TRPL) and Electrochemical Impedance Spectroscopy (EIS) studies.

Effects of polyethylene oxide particles on the photo-physical properties and stability of FA-rich perovskite solar cells

“…Unless otherwise stated, most of the materials used in this work were purchased from Sigma Aldrich and used as received. Apart from Polyethylene Oxide (PEO) polymer, all the other materials have been listed in our previous work on FA-Rich PSC 13 , 55 – 57 .…”

“…After sequential cleaning of pre-patterned FTO-coated glass substrate in a detergent, acetone, and IPA, a compact electron transport layer (ETL) was formed from mixed titanium dioxide (TiO 2 ) and tin (iv) oxide (SnO 2 ) precursor solutions following the procedure described elsewhere 55 . The SnO 2 and TiO 2 in the ETL precursor solution was mixed in the volume proportion of 0.2 (optimized from previous work) before being spin coated onto the FTO coated glass substrate 57 .The perovskite active layer was formed on the ETL via a two-step spin-coating process where the lead (II) Iodide (0.5993 g in 1 ml of mixed DMF-DMSO solvent) was first spin-coated, followed by the organic components that were mixed with PEO in different weight proportions. The organic component consisted of a mixture of FAI, MACl and MABr in the ratio of 10:1:1 by mass (60 mg, 6 mg and 6 mg) respectively 13 , 55 .…”

Adhesion in Perovskite Solar Cell Multilayer Structures

“…EIS − was used to obtain insights into the charge carrier dynamics across the interfaces of PSCs in this study. A semicircle from high to low frequency regions is observed for all PSCs and are fitted to the appropriate equivalent circuit shown in Figure A (inset).…”

Metal-Doped TiO2 Thin Film as an Electron Transfer Layer for Perovskite Solar Cells: A Review

“…The results showed perfect alignment of the conduction band with the adjacent perovskite layer (Figure 5d) and the reduction of the defect density at the interface and in the entire film [89]. Koech et al (2021) also reported that an increase of 7.16% PCE was attained in an SnO2-doped TiO2 ETL structure, resulting in an average PCE of 17.35% ± 1.39% as the result of improved electron extraction and transport ability [90]. A previous study by Gu et al (2017) reported the doping of Fe 3+ into TiO2 to improve the conductivity of TiO2 compact layers and finally boost the performance of PSCs to attain an efficiency of 18.6%.…”