Polymer-Chain Aggregation-induced Electrical Gating at the H- and J-aggregate P3HT

초록

This research explores how aggregation influences the electrical behavior at both the planar -heterojunction poly(3-hexylthiophene) (P3HT)/SiO2 and P3HT/ZnO nanocrystal (NC) interfaces. Theformation of H- and J-type aggregates leads to distinct molecular ordering and packing structures,manifesting as changes in threshold voltage shifts (electrical gating) as well as absorption and luminescenceproperties. Ultrasound irradiation (sonication) significantly alters the molecular arrangement in P3HT,favoring the formation of H-aggregates over the typically formed J-aggregates. In pristine P3HT, J-aggregatesfacilitate efficient exciton movement and electrical generation, resulting in higher photocurrents compared tosonicated-P3HT, which predominantly forms H-aggregates. Field-effect transistors (FETs) based on sonicatedP3HT exhibit a more positive threshold voltage and increased mobility, indicating the presence of more mobilecharge carriers, even in the absence of an applied voltage. In interfaces with ZnO NC, pristine P3HTdemonstrates a considerable shift in threshold voltage under illumination, attributed to electron trapping. Conversely, sonicated P3HT interfaced with ZnO NC shows less electron trapping and minimal change inthreshold voltage. This study underscores how the type of aggregate (H or J) in P3HT significantly dictateslight-induced electrical gating. Ultrasound irradiation (sonication), while enhancing mobility by improvingcrystallinity, leads to a decrease in photocurrent efficiency in H-aggregates compared to the J-aggregatespresent in pristine-P3HT.

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