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Singlet exciton diffusion was studied in the efficient organic photovoltaic electron donor material DTS(FBTTh). Three complementary time-resolved fluorescence measurements were performed: quenching in planar heterojunctions with an electron acceptor, exciton-exciton annihilation, and fluorescence depolarization. The average exciton diffusivity increases upon annealing from 1.6 × 10 to 3.6 × 10 cm s, resulting in an enhancement of the mean two-dimensional exciton diffusion length (L = (4Dτ)) from 15 to 27 nm. About 30% of the excitons get trapped very quickly in as-cast films. The high exciton diffusion coefficient of the material leads to it being able to harvest excitons efficiently from large donor domains in bulk heterojunctions.
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http://dx.doi.org/10.1021/acsami.6b16487 | DOI Listing |
J Phys Chem Lett
September 2025
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, Jinan 250014, P.R. China.
Metal halide perovskites have garnered significant attention due to their exceptional photoelectric properties. The alkali metal doping strategy has been demonstrated to effectively modulate grain size, control crystallization kinetics, and adjust band gap characteristics in perovskite. This study employs the first-principles calculations to reveal that the selection of alkali metal species and their corresponding doping methodologies exert markedly distinct influences on both the electronic properties and ion migration kinetics of CsPbBr perovskites.
View Article and Find Full Text PDFACS Appl Mater Interfaces
September 2025
National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
For optoelectronic devices based on lead-halide perovskites and other semiconductors, a comprehensive understanding of the electric field influences on the carrier transport characteristics is critical to the optimization of their practical performances. To fulfill this challenging goal, here we have employed photoluminescence spatial image and transient absorption microscopy measurements on an individual CsPbBr microplate biased at external voltages in an Au/CsPbBr/Au device. At the subpicosecond time scale, some photogenerated excitons are dissociated into free electrons and holes that drift toward the electrodes to leave behind unfilled defect sites, which are capable of scattering the residual excitons to yield a reduced diffusion coefficient.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2025
College of Polymer Science and Engineering, State Key Laboratory of Advanced Polymer Materials, Sichuan University, Chengdu, 610065, P.R. China.
Simultaneous promotion of charge and mass transportation between catalytic centers and reactants is crucial for photocatalysis but remains a substantial challenge on account of the widespread use of homogeneous or heterogeneous photocatalysts that suffer from sluggish reactant-diffusion kinetics or interfacial electron-transport resistance, respectively. Herein, we demonstrate the construction of conjugated microporous polymer aerogels as available quasi-homogeneous photocatalysts by integrating structural designability, which allows for the incorporation of electron-acceptor building blocks featuring ultralong-lived excitons as high-concentration local catalytic centers, and hierarchically porous gel networks that wrap solvent and reactants to provide a "single" reaction phase without interfacial resistance. A total of 18 samples of C─H functionalization reactions underpinned by four different mechanisms were screened to showcase the general applicability of the obtained aerogel photocatalysts, which achieved remarkable conversion efficiencies, gram-scale productivities, and recyclability.
View Article and Find Full Text PDFNat Commun
August 2025
State Key Laboratory of Chemical Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
Charge-transfer (CT) states with long transport distances are highly desired for promoting the performance of organic optoelectronic devices in photoconversion and electroluminescence. However, due to the limited lifetime and small diffusivity, only nanoscale CT transport has been observed so far. Herein, taking a binary CT cocrystal (trans-1,2-diphenylethylene-1,2,4,5-tetracyanobenzene, named as T-T) with efficient thermally activated delayed fluorescence (TADF) as a model material, we report the direct observation of long-distance CT exciton transport by using modified time-resolved and photoluminescence-scanned imaging microscopy, which reveals a triplet-assisted CT transport mechanism.
View Article and Find Full Text PDFAdv Mater
August 2025
School of Electrical Engineering, University of South China, Hengyang, 421001, China.
Industrial-scale roll-to-roll processing of organic photovoltaics (OPVs) requires photoactive layers ≥300 nm for manufacturability and mechanical robustness, yet state-of-the-art high-efficiency systems remain confined to 80-120 nm due to intrinsic exciton diffusion and charge transport limitations. To resolve this fundamental thickness-efficiency trade-off, monolayer MnPS nanosheet (1-2 nm) via liquid-phase exfoliation are engineered to extend exciton diffusion lengths and out-of-plane charge mobility, as validated through multimodal characterization. The optimized PM6:Y6:MnPS system achieves record efficiencies of 19.
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