CLIMATE-SPECIFIC RELIABILITY OF LEAD-FREE PEROVSKITE SOLAR CELLS IN INDIA: A CRITICAL REVIEW OF DEGRADATION MECHANISMS, TESTING PRACTICES, AND EVIDENCE GAPS

Abstract

Lead-free perovskite solar cells (PSCs) are being investigated as alternatives to lead-containing photovoltaic absorbers because of concerns about lead toxicity and the need for more sustainable solar-energy technologies. Their practical deployment, however, depends not only on initial power-conversion efficiency but also on reliable operation under heat, moisture, oxygen, illumination, electrical bias, and combined environmental stress. This critical review frames the reliability question around the relevance of published stability evidence to hot and seasonally humid climates such as those found in India. It considers tin-, bismuth-, antimony-, and germanium-based absorber families, identifies the principal physical and chemical degradation pathways, and examines why results obtained using different test conditions cannot always be compared directly. Recent reviews have already examined lead-free perovskite stability broadly; therefore, the distinctive contribution proposed here is a climate-relevance and evidence-quality lens rather than a claim that no prior stability review exists. The available literature indicates that tin-based systems face oxidation and defect-related challenges, while several bismuth- and antimony-based systems often trade improved environmental robustness for less favourable charge transport or band-structure characteristics. Accelerated ageing is valuable for screening but cannot, by itself, establish field lifetime. The paper proposes a transparent literature-screening method and a data-extraction framework covering absorber composition, encapsulation, temperature, relative humidity, illumination, bias, duration, and performance retention. A key conclusion is that meaningful comparison requires standardised reporting and longer-duration outdoor studies, including climate-specific datasets. The manuscript is a critical narrative review framework; its final submission should follow a completed, reproducible database search and verification of every included study.
Keywords: lead-free perovskite solar cells; stability; degradation physics; tin perovskites; outdoor testing; hot-humid climate; photovoltaic reliability; India