Abstract
Semitransparent perovskite solar cells (STPSCs) have excellent potential for widespread application as building integrated photovoltaics. Widespread application of STPSCs could result in decreased CO(2) footprints for buildings. Unfortunately, STPSCs tend to have poor aesthetic qualities (being usually red-brown in color) and low stability. Building on our previous work, here we use new poly(N-isopropylacrylamide) microgels (PNP MGs) to provide highly ordered non-close packed arrays within perovskite films that reflect some of the incident light to provide structural color to STPSCs. (MGs are swellable crosslinked polymer colloid particles.) We introduce PNP MGs into two different perovskites and achieve a wide gamut of reflected color and iridescence from the perovskite films. Devices containing the MGs have average visible transparency (AVT) values of greater than 25%. The best PCE for a MG-containing STPSC is 10.60% compared to 9.14% for the MG-free control. The MGs not only introduce structural color to the STPSCs but increase the PCE and stability. Equations are provided that enable the reflected color to be predicted from the formulation used to deposit the films. Our work shows that the self-ordering tendency of PNP MGs gives a viable new method for introducing structural color into STPSCs. Because our one-step method for introducing structural color into STPSCs is general, does not introduce any additional processing steps and is scalable whilst also improving device stability, this study may bring deployment of STPSCs closer.