High-performance Layer-by-Layer Processed Polymer Solar Cell via Solid Additive of Thermally-activated Delay Fluorescence

Simultaneously optimizing the optoelectronic properties and the morphology of active layer is the key to high-performance polymer solar cells. Here, we present a novel materials-processing paradigm that incorporates a thermally activated delayed fluorescence (TADF) additive into the layer-by-layer (LBL) fabrication process to concurrently optimize nanoscale morphology and mitigate non-radiative recombination. We demonstrate that the TADF additive facilitates the formation of an ideal interpenetrating network during LBL film deposition, while its intrinsic TADF properties effectively reduce non-radiative voltage loss, enhance exciton lifetimes, and facilitate charge generation and transport. Devices fabricated with this synergistic strategy achieve both high short-circuit current density and open-circuit voltage, culminating in a remarkable power conversion efficiency exceeding 20%. This work not only provides an efficient and reproducible processing route for high-performance polymer solar cells (PSCs) but also opens a new avenue for addressing fundamental optoelectronic limitations through coordinated material design and processing innovation.