Optimization of a Planar Perovskite Solar Cell Layer Thicknesses: Optical and Electrical Effects

In this paper, the layer thicknesses of a planar perovskite solar cell (PSC) are computationally optimized. Layer thickness optimization is important for all thin film solar cells to maximize photogeneration and charge extraction which typically react in opposite ways to an increasing absorber layer thickness. Moreover, charge transport layers also affect device operation. The thickness of one functional layer may affect the optimal thickness of another. The thicknesses of perovskite (PVK) and hole transport layer (HTL) showed correlated behavior meaning that the optimal PVK thickness changed by altering the HTL thickness. Correlation between the preferred thicknesses of the electron transport layer (ETL) and PVK or HTL was not observed. Instead, the thinnest ETL resulted in the best performance in all cases. The correlation between the optimal PVK and HTL thicknesses mainly arose from device optics, that is, absorption and photogeneration, and the correlation sustained in optoelectronic operation. Charge transport model was, however, required to find the true optimum because PVK thickness is not bounded by the optical operation. Based on the results, it is recommended to optimize rear transport layer and PVK thicknesses simultaneously considering both optical and electrical operation and minimize front transport layer thickness.