Numerical analysis and performance optimization of a poly(3-hexylthiophene):polynaphthalene-bithiophene heterostructure device using SCAPS-1D simulation

Abstract

A detailed numerical investigation on a P3HT:N2200 bulk heterojunction (BHJ) organic photovoltaic device was carried out using the one dimensional Solar Cell Capacitance Simulator (SCAPS-1D) tool to analyze the impact of materials and physical parameters on overall photovoltaic device performance. For the simulation analysis, we employed the photovoltaic device architecture of ITO/PEDOT:PSS/P3HT:N2200/BCP/Al, where PEDOT:PSS and BCP were used as the hole transport layer (HTL) and electron transport layer (ETL), respectively. For the comparison between BHJ and bilayer structured devices, a bilayer photovoltaic device was modelled using P3HT and N2200 semiconducting polymers as donor and acceptor layers, respectively. The superior performance of the BHJ device compared to the bilayer structured configuration motivated us to focus further investigation on the BHJ architecture. The physical and electrical parameters such as thickness, bandgap, electron and hole mobility, electron affinity, and doping density both for donor and acceptor types of the P3HT:N2200 BHJ layer were systematically varied to inspect their impact on the photovoltaic parameters. Furthermore, the role of interface defect densities at the HTL/P3HT:N2200 layer and P3HT:N2200/ETL interfaces was investigated. Additionally, the impact of bulk defect density at the P3HT:N2200 layer was investigated. Finally, the roles of operating temperature and series and shunt resistance were also studied. The simulated BHJ device exhibited a J_SC of 15.029 mA cm⁻², V_OC of 0.699 Volt, FF of 74.684% and PCE of 7.845%, whereas the bilayer structured device showed a PCE of 1.79% only with 5.952 mA cm⁻² short circuit current density. Simulation results reveal that increasing the thickness of the P3HT:N2200 layer from 50 nm to 500 nm significantly improves the overall device PCE. Following systematic optimization of the physical and electrical parameters of the P3HT:N2200 BHJ layer, the optimized device exhibited photovoltaic device parameters of J_SC = 19.573 mA cm⁻², V_OC = 1.092 V, FF = 55.371% and PCE = 11.834%.