High efficiency semitransparent perovskite solar cells containing 2D nanopore arrays deposited in a single step

Semitransparent perovskite solar cells (STPSCs) continue to attract enormous interest because of their potential to provide low-cost renewable energy for building and automotive applications. Whilst many studies have shown that small molecule additives can improve STPSC properties, here we use relatively colossal poly(N-isopropylacrylamide) microgel particles (MGs) as polymer colloid sponge-like additives for the first time. Uniquely, these MGs have an inherent tendency to form highly ordered 2D non-close-packed particle arrays when deposited. Remarkably, this morphology is transcribed to the perovskite layer in the form of 2D non-close-packed nanopore arrays. The nanopores contain shunt-blocking MGs. The perovskite/MG-based STPSCs devices achieve a champion power conversion efficiency (PCE) of 11.64% for a device average visible transmittance (AVT) of 25.3%. The average light utilization efficiency (LUE) for the optimum system is 2.60% which is much higher than that for the MG-free control system and is larger than the 2.50% threshold that is required, in principle, for application. The MGs bind to the Pb2+ ions and passivate the perovskite film. Finite difference time domain (FDTD) simulation data show that the MGs increase the AVTs of the films compared to uniform MG-free films. The MGs are proposed to act as nanoscale optical windows. Our new approach to preparing STPSCs delivers perovskite films containing 2D nanopore arrays in a single step that provide improved PCEs and AVTs and may accelerate future STPSC applications.