Improvement in conductivity of lead-free CH3NH3SnI3 perovskite thin film using multi-walled carbon nanotubes as a transporter

Abstract

CH3NH3SnI3 is a lead-free perovskite material that gains significant attention due to its favourable properties for optoelectronic device applications. It is a potential replacement for lead-based perovskite materials. However, the presence of traps, defects, and oxidation vacancies within these perovskite-based devices hinders the flow of charge carriers, causing them to become trapped or recombined within the device before reaching the electrodes. This limits the electrical performance of the device. To address this issue, this study focuses on improving the electrical performance of CH3NH3SnI3 perovskite by incorporating MWCNTs. Thin films of CH3NH3SnI3 perovskite were prepared both with and without MWCNTs. By employing the Van der Pauw method, resistivity measurements revealed that the electrical conductivity of the film increased to 7.80 × 10−2 S/m with the presence of MWCNTs, compared to 8.4 × 10−4 S/m without them. I-V measurements of the thin films-based Schottky devices showed that the conductivity increased from 1.21 × 10−5 S/m to 1.02 × 10−4 S/m with MWCNTs, while the barrier height decreased from 0.51 eV to 0.43 eV, and the ideality factor decreased from 4.01 to 2.56. The improved electrical performance observed when MWCNTs were incorporated, suggested that they formed a charge transfer pathway for carriers within the perovskite material. This pathway reduced trap energy, enabling charge carriers to percolate between grains and reach the electrodes. These findings highlight the significance of MWCNTs as a means to enhance the charge transfer dynamics in environmentally friendly CH3NH3SnI3 perovskite-based devices. Such improvements have promising implications for the development of future perovskite-based devices.