Unlocking Photoluminescence in 6,13-Bis(triisopropylsilylethynyl)pentacene: Singlet Fission Mitigation by 2D Material-Controlled Molecular Packing.

Cheng, Zhichao; Zheng, Han; Guo, Jing; Wang, Qi; Duhm, Steffen; Koch, Norbert; Cheng, Hui-Ming; Yu, Kuang et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

Organic photoluminescent semiconductors hold significant potential for bioimaging, sensing, and light emitting devices. However, their practical use in optoelectronics is often limited by aggregation-caused quenching (ACQ) that drastically reduces the photoluminescence (PL) quantum yields in densely packed solids. Here we report the controlled molecular packing of 6,13-bis(triisopropylsilylethynyl)pentacene (TPn), a model organic semiconductor that typically exhibits negligible PL due to ultrafast singlet fission in its crystalline form. Using monolayer WS<sub>2</sub> (ML-WS<sub>2</sub>) as a growth substrate, we induced a transition from a standing-up to a reclining molecular orientation of TPn interfacial layers, effectively suppressing singlet fission and unlocking its PL emission. The type-I energy level alignment at the TPn/ML-WS<sub>2</sub> heterointerface further enhances TPn emission by exciton energy transfer from ML-WS<sub>2</sub>. This work provides an effective approach for tailoring the molecular packing of weakly emitting π-conjugated solids using two-dimensional nanomaterials, facilitating their application in optoelectronic devices.