To study optoelectronic and structural properties of doped titania thin films for perovskite solar cells

Abstract

Perovskite solar cells (PSCs) are rapidly emerging as efficient solar cells due to their efficient photovoltaic and physiochemical properties. Ideally, the absorber layer in PSCs is sandwiched between highly conductive electron transport layer (ETL) and highly stable hole transport layer (HTL). The interfaces between these layers highly affect the performance of PSCs. In this study, Mg doped TiO2 films were synthesized by the solgel method and applied as an electron transport material for perovskite solar cells (PSCs). The materials were characterized by XRD, Raman, SEM, AFM TGA and FTIR to analyze its suitability for PSCs. Morphological and structural studies of thin films revealed that Mg doped thin films were quite homogenous, crack free and the Mg doping into titania was successful. Opto- electronic studies show the improvements in absorption and band gap reduction after doping with Mg. Electrical properties were studied by photocurrent density-voltage (J-V) analysis and electrochemical impedance spectroscopy (EIS) measurements. It was observed that with Mg doping, uniformity of TiO2 based ETL film significantly improved thereby providing an interface for the growth of absorber layer. Optoelectronic studies suggested that band gap is effectively reduced in the sequence with the addition of Mg and absorption range is also enhanced. In electrical analysis, Mg doped titania based ETL shows enhancement in conduction and sheet carrier mobility as compared to undoped TiO2 films. J-V results indicated more than two-fold increase in photovoltaic efficiency for3 wt% Mg doped TiO2 thin films.