Executive Summary : | Hybrid perovskite solar cells(PSCs) have setup a remarkable benchmark among the next-generation solar cells, owing to low-cost, simple fabrication, tunable band gap, intense absorption coefficient, long carrier diffusion lengths. The recorded value of power conversion efficiency(PCE) of PSCs has reached upto 25.6% in 2022. Although their efficiency has increased rapidly, a number of obstacles such as poor stability and toxicity of lead-based PSCs must yet be overcome before they can be considered a viable commercial technology. Hence, adopting lead-free perovskites are in demand. Recent studies on improving the stability issues report the strategies such as optimization of device architecture, adopting novel mixed-halide-perovskites, and suppression of surface traps via surface engineering. Despite sincere efforts to improve the device lifetime, the degradation mechanism is yet to be unraveled. During the fabrication process, perovskite films deposition tends to develop defects within the film as well as at the interfaces. During the operation, these defects may lead to trapping of photo-charge carriers which impedes their separation and transport, and hiders the collection. Besides, the interfaces experience undesired chemical reactions and mechanical delamination problems. In view of this, recent studies have witnessed the promising potential of colloidal quantum dots(QDs) such as carbon, CuS, and semiconducting QDs, due to their prominent tunable optoelectronic properties and simple preparation techniques. Among these, semiconducting QDs are considered as most promising for PSCs, owing to their size-dependent bandgap tunability, high carrier mobilities, good optical properties, intense light harvesting property, quantum confinement, and excellent structural stability. Research has proved that their use in PSCs especially, ZnO, PbS, CdS, CdSe QDs, either in between ETL/perovskite interface or at perovskite/HTL interface, help in achieving improved PCE, and simultaneously address the problems related to interfacial defect, charge-transfer, interfacial recombination, chemical stability difficulties. Currently, surface passivation of the perovskite layer via introducing core/shell semiconductor QDs has offered a great advantage particularly the energy transfer for photoresponsivity enhancement, surface defect-suppression, better energy-level alignment with the surrounding layers, and excellent photostability. In tune with this, the proposed work will develop PSCs fabricated under ambient-air environment with better efficiency(15-20%) and long term-stability(~5000 hours) onto a large active area (1 cm²). Perovskite layer will be deposited by thermal CVD technique to ensure defect free growth. Surface passivation of these CVD grown-perovskites will be carried out by depositing two kind of colloidal CdSe/ZnS and CdSe/ZnTe/ZnS QDs for enhancing the optical and electrical properties and also protecting the surface from the moisture in air. |