Impact of Charge Extraction on Current-Voltage Characteristics of Perovskite Solar Cells

Abstract This work presents an extended Shockley equation (ESE) to elucidate the impact of charge extraction on the current density voltage (J–V) characteristics of perovskite solar cells (PSCs). In the ESE, the driving forces of charge extraction are described by explicit voltage drops across the transport layer and at the contacts, which consume the electromotive force established by the maximum quasi-Fermi level splitting. As a result, the ESE can efficiently produce the J–V curves showing excellent agreement with the exact results by the drift-diffusion simulations. Based on the ESE, we studied the impact of charge extraction on the shape of the J–V curves and identified three types of J–V curves. We also revealed the complicated relationship between the realistic material parameters and the performance of the PSCs. The results show that the ESE accurately relates the material and contact properties to the power conversion efficiency of the PSCs. Then, we used the ESE inversely to quantitatively determine the efficiency losses due to the impact of charge extraction from the measured J–V curves of the PSCs with spiro-OMeTAD or NiO x as the hole transport layers. Our results suggest that the ESE provides a simple alternative way to model the PSCs precisely. This work could contribute to the understanding of the PSCs and the processing of new efficient transport layers.