Lignin carbon dot/nanocellulose films for enhanced UV stability and efficiency in perovskite solar cells through selective light transmission, blocking, and conversion

Perovskite solar cells (PSCs) are promising candidates for solar energy harvesting, but their poor UV stability poses a significant challenge. In this work, we developed lignin carbon dots (L-CD) embedded in nanocellulose (CNF) films to improve both the UV stability and efficiency of PSCs. The nanoscale CNF fibers provide high transparency to the films, allowing the transmission of visible (VIS) and most infrared (IR) light. Meanwhile, the aromatic structure of L-CD enables effective light absorption, blocking harmful UV and a portion of IR light. This combination ensures sufficient solar radiation while suppressing UV-induced degradation, increasing the retained efficiency of PSCs from 35% to 58%. Notably, the blocked UV and IR light was converted into VIS light, further boosting device performance. Key parameters, including short-circuit current density (J_SC), fill factor (FF), external quantum efficiency (EQE), and power conversion efficiency (PCE), were significantly enhanced. With the unique effects of optimal light transmission, blocking, and conversion, the L-CD/CNF films effectively mitigate UV exposure and broaden the range of solar light utilization, offering a green, cost-effective, and efficient strategy for fabricating high-performance PSCs.