Influence of SWCNT on the Electrical Behavior of an Environmentally Friendly CH3NH3SnI3 Perovskite-Based Optoelectronic Schottky Device

Abstract

The lead-free tin-based halide perovskite CH3NH3SnI3 has recently been explored in a wide range of optoelectronic device applications. However, the charge conduction process of the CH3NH3SnI3 perovskite layer is hindered by the presence of vacancies resulting from tin oxidation, sample defects, and trap states, which limit the performance of the device. In this study, we introduced single-walled carbon nanotubes (SWCNTs) into the perovskite to enhance the charge conduction of the device. To demonstrate this, CH3NH3SnI3 perovskite and its composites with SWCNTs were synthesized and used as an active layer in a sandwich-structured device. Electrical measurements show that the device based on SWCNTs exhibits superior performance compared to the device consisting solely of perovskite. Incorporating SWCNTs into the device improves conductivity and reduces series resistance. Specifically, in the absence of light, SWCNTs increase the conductivity from 3.8 × 10–5 to 1.6 × 10–4 S/m and decrease the series resistance from 348.25 to 34.80 Ω. Under illumination, SWCNTs further increase conductivity to 4.0 × 10–4 S/m from 8.1 × 10–5 S/m and decrease series resistance to 19.20 Ω from 220.56 Ω. The results suggest that SWCNT can serve as a channel for charge extraction. An analysis of space charge limited current (SCLC) conduction indicates that incorporating SWCNT decreases the trap energy from 103.22 to 79.70 meV under dark conditions. This implies that SWCNT also acts as a filler for trap states. Based on these findings, it appears that the SWCNT-CH3NH3SnI3 perovskite composite has the potential to yield high-performance optoelectronic devices. This study presents an intriguing approach for enhancing carrier transfer with minimal recombination loss and could serve as a source of inspiration for future research in the optoelectronics field.