Electrical property modified hole transport layer (PEDOT:PSS) enhance the efficiency of perovskite solar cells: Hybrid co-solvent post-treatment

Poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) layer as a hole transport layer (HTL) plays a key role in efficient hole extraction and transportation of the inverted planar perovskite solar cells (PSCs). However, the insulating nature of PSS lead to lower electrical property of the PEDOT:PSS film, which impedes transferring hole and results in a low photocurrent of the PSCs. In this work, dimethylformamide (DMF), methanol and their mixture solvents (co-solvent) were employed to treat the PEOT:PSS thin film after deposition with different methods to enhance the film's electrical conductivity. Electrical conductivity of the PEDOT:PSS films was increased from 10−3 S cm−1 to ~102 S cm−1 after the co-solvents treatment. Using the highest conductivity co-solvent treated PEDOT:PSS thin film as the HTL in a perovskite solar cell, the power conversion efficiency (PCE) of the device has been measured improved by 17.5% as compared with that of the control device with the untreated PEDOT:PSS film as the HTL. This result shows that the hybrid co-solvent post-treatment is a simple and feasible way to modified the electrical properties of the PEDOT:PSS film as the HTL for high efficient PSCs and other thin film electronic and optoelectronic devices.