Comparative investigation into effects of the interplay between absorber layer crystallinity and interfacial defect states on the performance of lead-based and tin-based perovskite solar cells

Abstract This report computationally investigates the relative influence of absorber layer crystallinity and the nature of interfaces in lead-based (toxic) and tin-based (non-toxic) perovskite solar cells using SCAPS-1D. The absorber layer crystallinity was modelled in terms of varying charge carrier mobility and defect density while the interfacial behaviour was modelled through varying defect density at the electron transport material (ETM)/perovskite and perovskite/hole transport material (HTM) interfaces. The results suggest that tuning of the aforementioned parameters plays a critical role in improving the efficiency of perovskite solar cells. In-depth analysis of the results elucidates that the performance of both types of simulated structure is critically dependent on the crystallinity of the perovskite absorber layer. Furthermore, the performance of the lead-based structure is more dependent on the nature of the ETM/perovskite interface than that of the perovskite/HTM interface while the tin-based structure is dependent on the nature of both the interfaces. Moreover, the tin-based structure reveals a possibility of achieving performance comparable/superior to that of its lead-based counterpart by reducing the defect density inside the absorber layer. The findings are key towards the performance enhancement in perovskite solar cells and especially tin-based perovskite solar cells, which are deemed to be a potential replacement for lead-based perovskite solar cells.