Balanced Intra- and Interchain Exciton Delocalization Enables Efficient All-Polymer Solar Cells
Year: 2026
Type: article
Abstract: Polymerized Y-type nonfullerene acceptors (PY-NFAs) have shown great promise for efficient and stable organic solar cells (OSCs), yet their excited-state dynamics and structure-photophysics-performance relationships remain unclear. Here, we investigate a series of PY-NFAs and distinguish between intrachain excitons (intra-Ex) and interchain excitons (inter-Ex) formed in the solid state using cryogenic transient absorption (TA) spectroscopy at 100 K. We identify the emergence of trapped intra-Ex in the PY-NFA films from approximately 100 ps onwards after photoexcitation. By comparing this low-temperature TA signal among different PY-NFA films, we uncover a strong correlation between the trapped intra-Ex signature and the performance of these PY-NFAs in donor-acceptor blend OSC devices. This correlation indicates that the low-temperature TA response provides a quantitative measure of structural disorder in the PY-NFA aggregates and in the corresponding donor-acceptor blends. Correlating these spectroscopic results with molecular packing and morphological data, we reveal that high-performance PY-NFAs simultaneously exhibit (1) extended backbone conjugation and large intrachain exciton bandwidths and (2) uniform, oriented interchain packing despite moderately increased - stacking distances. These findings provide new design rules for PY-NFAs and offer deeper insight into how structural disorder and exciton dynamics govern OSC performance.
Source: PRX Energy
DOI: 10.1103/fls9-jc34
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7160105799