Synergistically improving open-circuit voltage and fill factor via utilizing a natural pigment as efficient interconnect layer for high-performance perovskite-organic tandem solar cells

Cathode interfacial layer (CIL) plays an indispensable role in improving power conversion efficiency (PCE) for perovskite solar cells (PSCs). To acquire low-cost, environmentally friendly and effective cathode interfacial materials (CIMs), a natural pigment, laccaic acid (LA), is utilized as CIL for achieving high-performance PSCs. Attributing to the introduction of LA CIL, the work function ( WF ) of silver cathode is decreased obviously, leading to better interfacial ohmic contact. This lower WF in cathode could facilitate electron transport, resulting in distinct suppression in charge recombination and energy loss. As a result, the introduction of LA CIL improves the photovoltaic performance effectively in 1.77 eV wide bandgap PSCs with a high open-circuit voltage ( V OC ) of 1.32 V, a high fill factor (FF) of 81 % and a PCE of 18.48 %. Interestingly, LA shows a broad application as interconnect layer (ICL) in perovskite-organic tandem solar cells (POTSCs), in which it results in a high PCE of 23.51 % with a V OC of 2.15 V. This V OC is one of the highest values in POTSCs. Hence, LA exhibits a promising feature as a natural product to construct CIL and ICL in solar cells for realizing a low-cost, green and sustainable photovoltaic technology. • A natural pigment (LA) was utilized as a green interconnect layer in POTSCs. • LA showed the novel merits in low cost, nontoxicity and sustainability. • LA decreased the work function of silver cathode efficiently.