Improving perovskite/P3HT interface without an interlayer: Impact of perovskite surface topography on photovoltaic performance of P3HT-based perovskite solar cells

The photovoltaic performance of poly(3-hexylthiophene) (P3HT)-based perovskite solar cells is inferior due to the improper perovskite/P3HT interface caused by a surface energy mismatch. The most promising method to improve the interface is the introduction of interlayers between perovskite and P3HT layers; however, this increases fabrication complexity and irreproducibility. Here, we show how the surface topography of the perovskite layer can improve the interface without an interlayer. To explore this, we varied surface topography by altering the crystal size of the methylammonium lead iodide through its deposition temperature namely, 10 0C and 30 0C. The solar cells based on the perovskite layers formed at 10 0C outperform the cells fabricated from perovskite layers deposited at 30 0C. Our studies reveal that the surface topography of the perovskite layer influences the surface energy that impacts the interface between perovskite and P3HT layers, consequently enhancing recombination resistance, short-circuit current, and open-circuit voltage, ultimately improving photovoltaic performance. Modification of surface topography is a simple approach to improve the perovskite/P3HT interface without an interlayer and can lead to better performance in P3HT-based perovskite solar cells.