An efficient ALD- and noble metal-free charge recombination architecture for monolithic all-perovskite tandem solar cells

Abstract

The currently efficient all-perovskite tandem solar cells (all-PTSCs) are built on the workhorse charge recombination layers (CRLs) composed of ALD-SnO_X/noble metal/PEDOT:PSS. However, the susceptibility of optoelectronic properties of SnO_X to the atomic growth conditions and the use of rare metals constrain their promise for commercial deployment. Here, we design an efficient and robust CRL consisting of a layer sequence of Cr/ITO/PEDOT:PSS. The conformally grown thin Cr layer serves as a critical barrier to protect the underlying perovskite from damage during sputtering ITO. Essentially, the entire stack of the CRL exhibits superior resistance to strong polar solvents during deposition of top narrow-bandgap perovskites. On these bases, high-performance monolithic all-PTSCs are reproducibly fabricated, yielding a state-of-the-art efficiency of 26.56%, alongside an impressive fill factor (FF) of 80.6%.