PEDOT:PSS-Nafion/n-Si Hybrid Heterojunction TOPCon Solar Cells: Experiment and Simulation

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most popular hole transport materials for replacing traditional high-temperature boron diffusion technology due to its low cost and easy preparation. However, pristine PEDOT:PSS has drawbacks, such as poor work function (WF) and poor film quality, which inhibit the improvement of cell efficiency. According to current research reports, a single dopant can improve only one of these two drawbacks. In this paper, we used Nafion to simultaneously improve the WF and wettability of PEDOT:PSS for preparing novel PEDOT:PSS/n-Si hybrid heterojunction solar cells with a tunnel-oxide passivated contact (TOPCon) back surface field structure, which we call PEDOT:PSS-Nafion (PPN)/n-Si hybrid heterojunction TOPCon solar cell. A cell efficiency of 11.08% was achieved after optimizing the ratio of PEDOT:PSS and Nafion. The three easily improved parameters, namely, series resistance (R-S), reflectivity, and WF, were studied and optimized through simulation, achieving a cell efficiency of 20.66%. To reduce R-S in the experiment, the Triton X-100-doped PEDOT:PSS film (PPTX) was introduced between the n-Si and PPN films to form highly conductive PPN/PPTX double hole transport layers, and the cell efficiency was increased from 11.08 to 13.7%. The experimental and simulated work presented a new thought and practical guidance for realizing low-cost, easy preparation, and high-efficiency silicon-based solar cells.