Interfacial engineering for efficient and stable two-terminal perovskite-based tandem solar cells

Two-terminal(2T)tandem solar cells(TSCs)are optically and electrically connected by two subcells with complementary bandgaps,which are designed to overcome the Shockley-Queisser(S-Q)limit of singlejunction solar cells.Organic-inorganic hybrid perovskites are ideal light-absorbing materials for 2T TSCs due to their tunable bandgaps,low-temperature solution-based processing,and excellent light absorption coefficient.Thus,2T perovskite-based TSCs(PTSCs)have aroused widespread interest among the photovoltaic community.At present,the key to obtaining efficient and stable 2T PTSCs is establishing efficient interfaces and layers with good photoelectric properties and high compatibility of subcells.In particular,interfacial engineering based on effective recombination layers(RCLs)and buffers has a prominent effect on achieving enhanced power conversion efficiency(PCE)of 2T PTSCs with improved operational stability.In this article,the current frontier issues of 2T PTSCs including different device structures and properties are reviewed in detail to analyze their merits,demerits and solutions to overcome bottlenecks.Subsequently,the component engineering,interface engineering and theoretical PCE analysis for designing 2T PTSCs proposed by material simulations are discussed.Furthermore,the scalability of interfacial passivation from single-junction perovskite solar cells to 2T PTSCs is evaluated,and the function mechanisms of RCLs and buffers are also summarized and analyzed carefully.Finally,the challenges faced by 2T PTSCs are pointed out,and their developme nt directions are suggested.This article aims to provide viable guidance for realizing practical manufacturing technologies for the commercialization of 2T PTSCs.