Enhancing Ambient Stability of Perovskite-Organic Tandem Solar Cells for IoT Applications

As the "Made in China 2025" strategy and Industry 4.0 advance, the prominence of cutting-edge information technology and eco-friendly manufacturing becomes increasingly pivotal. Central to this is the Internet of Things (IoT), which calls for technological refinement, particularly in the realm of energy supply. IoT devices, often subjected to variable conditions, demand high efficiency, stable operation voltage, and particularly robust environmental stability from perovskite solar cells as the energy supply candidate. However, while effective, the traditional encapsulation techniques are intricate and costly. In response, we propose the perovskite-organic tandem solar cell (POTSC), which has achieved over 25% photovoltaic conversion efficiency (PCE) and an output voltage of 2.1V, attracting significant research attention. Despite superior MPP tracking and thermal stability, the long-term environmental stability of these tandem cells has been less explored, posing a barrier to their IoT integration.<br/>Considering the p-i-n device architecture, the ambient stability of the POTSC is predominantly dictated by the back organic subcell, thereby imposing heightened demands on the organic active layer materials. Our study leverages an all-polymer bulk heterojunction (BHJ) to enhance both efficiency and stability. We introduce a novel polymer acceptor, PYSe2F-T, designed to absorb near-infrared light, broadening the absorption spectrum and boosting current density. Additionally, we optimize polymer packing with PffBQx-T by altering the polymerization sites, achieving a fill factor (FF) on par with the best polymer-small molecule BHJs. Notably, the all-polymer system exhibits superior performance in air processing, indicating its potential for the future fabrication of tandem solar cells and modules in ambient conditions. These innovations yield a PCE of 24.6% of the corresponding POTSC, resonating with leading research. The all-polymer device demonstrated exceptional ambient stability, maintaining 80% of its initial efficiency after 1000 hours in a ~50% humidity environment, unencumbered by encapsulation—a stark contrast to polymer-small molecule devices, which retained less than 50% of their initial performance. Cross-sectional SEM, photoluminescence (PL) mapping, and contact angle measurements illuminated the dense interpenetration framework of the proposed all-polymer blend, effectively shielding the perovskite subcell from atmospheric elements and enhancing overall stability.<br/> Our findings underscore the potential of all-polymer POTSCs as a sustainable energy solution for IoT. The demonstrated processing advantages and stability under ambient conditions suggest a promising future for the scalable fabrication of high-performance solar cells, propelling the IoT toward a new era of energy-efficient and environmentally benign technologies.