Executive Summary : | Halide perovskite semiconductors are light-absorbing materials with a specific crystal structure, AMX₃. They have shown potential for increased photoelectrochemical efficiency (PEC) and inexpensive solution processability in solar devices. Perovskite solar cells (PSCs) have reached a certified 25.5% efficiency since 2009. Organic-inorganic hybrid perovskite, MAPbI₃ and FAPbI₃, have dominated studies due to their high absorption and extinction coefficients, direct band gaps, carrier mobility, long charge-carrier diffusion length and lifetime, defect tolerance, and small exciton binding energy. However, they have limitations in long-term stability when exposed to moisture, air, heat, or light, causing efficiency losses over time. Various approaches have been implemented to improve efficiency, prevent intrinsic instability, tune bandgap, or resolve toxicity issues. Three-dimensional (3D) perovskites satisfying tolerance factor criterion are in the research limelight due to their excellent optoelectronic properties. Interfacial modification with layered and 3D materials can promote better charge transport properties. Perovskitoids can be derived from standard perovskite structures, featuring edge- and face-sharing motifs or combinations of all three connectivity. A suitable bulky organic cation in the perovskitoid crystal structure can improve charge carrier dynamics and restrain degradation. Recent reports show that perovskitoid stacked on 3D perovskite achieve appreciable efficiency, despite lag behind state-of-the-art PSCs. The major challenge is finding a potential cation candidate among ammonium salt or derivatives for the perovskitoid. |