Influence of bi-phasic TiO2 as a low-temperature curable electron transport layer for efficient perovskite solar cells

Abstract

Electron transporting layers play an important role in controlling the photovoltaic performance and stability of perovskite solar cells. Biphasic TiO2 nanoparticles are successfully synthesised by the solvothermal method. A low-temperature curable bi-phasic TiO2 layer consisting of brookite and rutile TiO2 was successfully developed by the spin coating technique. The effect of solvothermal synthesis's reaction time (5 h,10 h and 20 h) on brookite and rutile concentration is thoroughly studied. The optical, crystallographic and morphological properties are characterised effectively to analyse the bi-phasic nature of synthesised TiO2 nanoparticles. The effect of bi-phasic TiO2 nanoparticles concentration as an electron transport layer (ETL) in perovskite solar cells (PSCs) was studied by engineering a low-temperature curable TiO2 nanoparticle deposition methodology. The interparticle connection attained at low temperatures in brookite TiO2 is used to attain PSCs with high power conversion efficiency (PCE). The electrical properties and current–voltage measurements of the bi-phasic TiO2 ETL were evaluated thoroughly. PSC was fabricated with 75 % brookite and 25 % rutile TiO2 particles as ETL exhibited the highest PCE of 14 %, with an open circuit voltage of 1.1 V and a current density of 17.4 mA/cm2, which is effectively co-related with the change in brookite-rutile concentration.