Paving the Way to Building-Integrated Translucent Tandem Photovoltaics: Process Optimization and Transfer to Perovskite-Perovskite 2-Terminal Tandem Cells

While conventional opaque PV is hardly applicable to more than rooftops, transparent PV (TPV) promises energy harvesting at optimized average visible transmittance (AVT) and power conversion efficiency (PCE) without adversely affecting underlying facades, windows and buildings' residents. However, for successful market penetration, TPVs require an improvement in PCEs at optimized application-dependent AVTs to strengthen economic incentives. In particular, translucent PV, which is based on the segmentation of conventional opaque solar cells on transparent substrates and is thus distinguished by its technological flexibility, essential color neutrality, and ease of transparency variations, shows significantly over-proportional efficiency losses at AVTs above 20%. Furthermore, enhancement of neutral color rendering, sharpness of view and design flexibility is pivotal to increase its public acceptance. First, a high-throughput laser scribing setup is employed to micro-pattern translucent perovskite solar cells and submodules of up to 51 cm2 aperture area, enabling versatile transparent area formats and transparency variations. An in-depth analysis of electrical and optical performance using current-density-voltage-characteristics, laser-beam-induced current mapping and photoluminescence measurements result in optimal scribing parameters and transparent area formats, mitigating over proportional losses even at AVT levels above 20%. The resulting optimized translucent PV devices exhibit PCEs of up to 16.2% and 8.0% at 8.1% and 38.6% AVT, respectively. Varying transparent area formats and their spatial distribution, ideal designs regarding perception are validated by characterization of view through images regarding color rendering via UV/VIS-photospectroscopy and optical distortion via blind/referenceless image spatial quality evaluator algorithm (BRISQUE). Color rendering indices of up to 94 proof color neutrality at high perceptual quality of the corresponding view through images, ensuring a colorfast and crisp view for inhabitants when later applied in facades. Finally, the optimized micro-patterning process is transferred for the first time to 2-terminal perovskite-perovskite tandem cells, demonstrating feasibility as well as the future potential of high-efficiency translucent tandem PV by exploitation of their elevated Shockley-Queisser limit.