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Singlet fission (SF) is a charge carrier multiplication process that has potential for improving the performance of (opto)electronic devices from the conversion of one singlet exciton S1 into two triplet excitons T1 via a spin-entangled triplet pair state 1(TT). This process depends highly on molecular packing and morphology, both for the generation and dissociation of 1(TT) states. Many benchmark SF materials, such as acenes, are also prone to photodegradation reactions, such as endoperoxide (EPO) formation and photodimerization, which inhibit realization of SF devices. In this paper, we compare functionalized tetracenes R–Tc with two packing motifs: “slip-stack” packing in R = TES, TMS, and tBu and “gamma” packing in R = TBDMS to determine the effects of morphology on SF as well as on photodegradation using a combination of temperature and magnetic field dependent spectroscopy, kinetic modeling, and time-dependent density functional theory. We find that both “slip-stack” and “gamma” packing support SF with high T1 yield at room temperature (up to 191% and 181%, respectively), but “slip-stack” is considerably more advantageous at low temperatures (<150 K). In addition, each packing structure has a distinct emissive relaxation pathway competitive to SF, while the states involved in the SF itself are dark. The “gamma” packing has superior photostability, both in regards to EPO formation and photodimerization. The results indicate that the trade-off between SF efficiency and photostability can be overcome with material design, emphasize the importance of considering both photophysical and photochemical properties, and inform efforts to develop optimal SF materials for (opto)electronic applications.
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This content will become publicly available on August 28, 2026
Computational detection of articulation transients in clarinet performance
Accurate measurement of note-to-note transitions is essential for analyzing articulation in clarinet performance. Traditional methods rely on either subjective amplitude thresholds—such as the time between 5% and 95% RMS levels—or direct measurement of tongue-reed contact time using reed-mounted sensors. These approaches are limited by their dependence on user-defined parameters or invasive hardware. This study proposes a computational alternative: ΔT, a curvature-based metric defined as the time interval between surrounding minima in the second derivative of the mouthpiece pressure envelope. Using data from a sensor-equipped mouthpiece (SEM), we compare ΔT to both threshold-based timing (Tt) and tongue contact duration (Tc) across portato and staccato articulations. Our findings show that ΔT closely tracks both Tt and Tc in structured articulations, with minimal absolute difference and robust repeatability. These results support the use of ΔT as a non-invasive, objective, and reliable estimate of transition duration, enabling broader application in performance analysis, pedagogy, and real-time feedback systems. This research was funded by: National Science Foundation Grant 2109932.
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- Award ID(s):
- 2109932
- PAR ID:
- 10655169
- Publisher / Repository:
- Acoustical Society of America
- Date Published:
- Journal Name:
- Proceedings of meetings on acoustics
- Volume:
- 58
- Issue:
- 1
- ISSN:
- 1939-800X
- Page Range / eLocation ID:
- 035007
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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