Advances in core–shell quantum dot solar cells: Materials design, charge dynamics, and photovoltaic performance

Quantum dot sensitized solar cells (QDSSCs) are becoming some of the great possibilities of the next-generation photovoltaics because of the ability to tune their energy gap, high coefficients of absorption, and reasonably low manufacturing price. Nevertheless, the practical usage of this kind of solar cell is limited by surface defects, charge recombination, and low stability. Core-shell quantum dots overcome these issues through surface passivation, charge separation augmentation, and improvement of charge transport characteristics, along with stability. In this review, the latest developments in the field of core-shell QDSSCs are analyzed, including analysis of Type I, Type II, quasi Type II, and inverted Type I heterostructures and synthesis techniques as hot injection, SILAR and others. In this study, a significant breakthrough is reached by establishing a link between the core-shell band alignment types and photovoltaic coefficients such as ( J sc ), open circuit voltage ( V oc ), fill factor ( FF) , and power conversion efficiency (PCE). It quantifies the trade-off between efficiency and toxicity in heavy-metal containing QDs and environmentally friendly QDs. It is found that ZCISe/ZnSe Type I systems give the best certified PCE of 13.84%, while type II systems have excellent Jsc of more than 19 mA/cm², due to spatial separation of charges. Also, the authors identify the reasons for reduction in efficiency which include incomplete collection of carriers and recombination processes taking place between the interfaces. An action plan is developed to achieve the intended efficiency in 2024–2030 when the attention will be paid to using non-toxic QDs, which will not contain any heavy metals. Also, one should employ strategies focusing on shell structure and the interfaces.