Enhanced Perovskite Solar Cells Performance Through Surface Engineering Investigation of a Zn-Complex Based Hole-Transporting Materials

Interface Engineering plays a critical role in the performance of perovskite solar cells (PSCs). High-quality perovskite films with suitable hole transport properties of the hole-transporting materials HTMs are critical factors in obtaining high-performing PSCs. Small inorganic molecule HTMs have attracted considerable interest in PSCs because of their structural flexibility, operational durability, and good hole mobilities, but they suffer unsatisfied cell efficiency. In this work, a ligand <b>BT28</b> and its zinc-based coordination complex <b>BTZ30</b> were designed and synthesized as hybrid organic-inorganic structured HTMs for PSCs applications. Both HTMs exhibit similar optical and electrochemical properties. The mixed-halide perovskites can be grown uniformly with large crystalline grains on top of both HTMs. However, it is discovered that the BTZ30-based solar cell exhibited a higher power conversion efficiency close to 20%. This can be due to the higher hole mobility of <b>BTZ30</b> than that of BT28. The high hole mobility of <b>BTZ30</b> is attributed to low trap-assisted recombination and efficient charge extraction efficiency, indicating a good perovskite/HTM interface. The PSC fabricated with the metal-containing HTM <b>BTZ30</b> shows the best power conversion efficiency (PCE) of 19.50%, which is higher than the PCE of 18.01% from the PSC fabricated with its ligand and non-metal HTM <b>BT28</b>.