Next-generation quantum dot solar cells: advances in materials, device engineering and performance optimization.

Quantum dot solar cells (QDSCs) have emerged as promising next-generation photovoltaic technologies owing to their tunable bandgaps, strong light absorption, solution-processability and potential to surpass the Shockley-Queisser efficiency limit through multiple exciton generation (MEG). This review presents a comprehensive and critically structured overview of recent advances in QDSCs by integrating material development, device engineering, interface optimization, and stability enhancement strategies within a unified framework. Unlike previous reviews that primarily focus on individual material systems or device architectures, this work systematically correlates quantum dot absorber materials, electron and hole transport layers, electrode engineering, fabrication methodologies, and charge-transfer mechanisms with photovoltaic performance metrics. Emphasis is placed on the comparative analysis of PbS, CdSe, perovskite, graphene and environmentally benign quantum dots, highlighting their influence on efficiency, charge transport, stability, and scalability. In addition, recent developments in interface engineering, ligand exchange, surface passivation, core-shell structures, plasmonic enhancement, and hybrid architectures are critically discussed as key routes for suppressing recombination losses and improving long-term operational stability. Emerging trends including AI-assisted device optimization, tandem configurations, and environmentally sustainable QD materials are further evaluated to identify future commercialization pathways. Despite significant progress, challenges associated with toxicity, large-scale fabrication, and environmental stability continue to limit practical deployment. Overall, this review provides a comparative and future-oriented perspective that bridges materials science, device physics, and scalable engineering approaches, offering strategic insights for the development of efficient, stable, and commercially viable QDSCs for next-generation solar energy technologies.