Balancing electrical and optical losses for efficient 4-terminal Si–perovskite solar cells with solution processed percolation electrodes†
The unprecedented rise in efficiency of perovskite-based photovoltaics has sparked interest in semi-transparent devices, particularly for tandem structures. Despite promising reports regarding efficiency and reduced parasitic absorption, many devices still rely on processes from the gas phase, compromising both applicability and cost factors. Here, we report all-solution perovskite solar cells with improved infrared transparency ideally suited as top-cells for efficient multi-junction device configurations. We demonstrate the functionality of copper(I) thiocyanate as antireflective layer and as selective contact between the transparent conductive oxide and the perovskite. This concept allows us to fabricate an opaque device with steady state efficiency as high as 20.1%. By employing silver nanowires with robust environmental stability as the bottom electrode, we demonstrate different regimes of device performance that can be described through a classical percolation model, leading to semi-transparent solar cells with efficiencies of up to 17.1%. In conjunction with the implementation of an infrared-tuned transparent conductive oxide contact deposited on UV-fused silica, we show a full device average transmittance surpassing 84% between 800 and 1100 nm (as opposed to 77% with PEDOT:PSS as the selective contact). Finally, we mechanically stacked optimized perovskite devices on top of high performing PERL and IBC silicon architectures. The measured imputed output efficiency of the 4-terminal perovskite–silicon solar cell was 26.7% and 25.2% for the PERL–perovskite and IBC–perovskite, respectively.