Promising photovoltaic application of multi-walled carbon nanotubes in perovskites solar cells for retarding recombination

Abstract

A facile spray deposition method was developed to prepare a high-quality perovskite layer under ambient conditions. However, the performance is expected to be further improved with substrate and the hole transport layer (HTL) optimization and device structure, for instance. MWCNTs with incorporated spiro-OMeTAD exhibited J_sc of 22.13 mA cm⁻² and PCE of 10.42%. To infer the origin of the increasing J_sc and PCE, the optical absorption performance, charge transfer and recombination performance were investigated. τ, R_ct, R_rec as a function of voltage and EIS measurements revealed the lower transfer resistance and recombination rate in PSCs with MWCNTs compared with the PSCs without MWCNTs. The increased resistance in dark conditions and the dark J–V curves explain the slight changes in the V_oc. The SEM images showed that there were no MWCNTs aggregated on the surface of the spiro/MWCNTs composite layer and part of MWCNTs was uncovered by spiro-OMeTAD at the interface of HTM and Au electrode. The decreased I_D/I_G ratio from 0.90 to 0.68 demonstrated the increased interaction between MWCNTs and spiro-OMeTAD.