Review on halide perovskites: Progress, issues and prospects in the aspect of photovoltaic applications

Halide perovskites have recently shown greater potential towards dominance in next-generation photovoltaic technology. This is owing to their versatile optoelectronic properties, solution processability, and compositional flexibility. Since the past decade, they have demonstrated significant rise in power conversion efficiency, rivalling established silicon‑based technologies. In this review, we comprehensively examined halide perovskites as tunable materials for photovoltaic applications, paying particular attention to compositional, dimensional, interfacial, and defect‑engineering strategies that enable band‑gap modulation, performance optimization, and stability enhancement. Key material systems, including three‑dimensional, low‑dimensional, double, and lead‑free perovskites, are discussed in relation to their structural chemistry and optoelectronic behaviour. The review also reports current challenges such as ion migration, phase instability, lead toxicity, and operational reliability under real‑world conditions. Emerging directions including high‑entropy perovskites, machine‑learning‑assisted materials design, advanced operando characterization, and industrial scalability are also highlighted. This review aims to provide a unified perspective on the issues, tunability mechanisms, and prospects of halide perovskites, contributing to their advancement toward stable, environmentally responsible, and commercially viable photovoltaic technologies.