| Affiliation: | 1. Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 China School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 China;2. Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 China;3. College of Chemistry, Beijing Normal University, Beijing, 100875 China;4. Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Centre for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032 China |
| Abstract: | Modulating photophysical processes is a fundamental way for tuning performance of many organic devices. However, it has not been explored as an effective strategy to manipulate the thermoelectric (TE) conversion of organic semiconductors (OSCs) owing to their critical requirement to carrier concentration (>1018 cm−3) and the fact of low exciton separation efficiency in single element OSCs. Here, an electric field modulated photo-thermoelectric (P-TE) effect in an n-type OSC is demonstrated to realize a significant improvement of TE performance. The electrical and spectroscopy characterizations reveal that the electric field gating generates combined modulation of exciton separation, charge screening, and carrier recombination, which produces a more than ten times improvement of photoinduced carrier concentration. These coupled processes contribute to the unconventional Seebeck coefficient (S)-electrical conductivity (σ) trade-off relationship of the photoexcited films, therefore leading to a more than 500% enhancement in the power factor for n-type OTE semiconductors. This work opens a unique way toward state-of-the-art organic P-TE materials for energy harvesting applications. |
