Fully vacuum‐free semitransparent polymer solar cells for power‐generating window with pure achromatic appealing

Among the existing renewable independent energy sources, semitransparent (ST) solar cells have attracted attention owing to their ability to be integrated into the windows of buildings or vehicles. To realize not only practical electricity production but also esthetic appearance, we fabricated PTB7:PC71BM-based ST polymer solar cells via fully vacuum-free and low-cost manufacturing methods. Fully vacuum-free manufacturing could be achieved from a silver nanowire and conductive polymer-based transparent lamination top electrode, thereby achieving complete and concrete electrical contact with the underlying polymer bulk-heterojunction layer through a simple hot-press lamination step. In addition, for the insertion of an appropriate hole-extracting interlayer between the lamination electrode and polymer layer, ST solar cells with a lamination electrode provided the best power conversion efficiency (PCE) of 4.36% with a fill factor (FF) of 53.9%. For comparison, opaque solar cells with a metal top electrode were also fabricated, providing the best PCE of 9.07% with an FF of 65.4%. However, the inferior electricity production of these ST solar cells can be compensated for by its pure achromatic appeal owing to its superior optical properties. Detailed optical analysis was performed to evaluate the compatibility of the lamination electrode-based ST solar cells for power-generating window applications. ST solar cells did not exhibit a noticeable optical cavity resonance effect, resulting in an extremely good visual appearance with achromatic sensation and a window illumination source with luminosity of 38.1%, CCT of 6480 K, and general CRI of 95.5 under D65, which is a standard daylight illuminant.