Exciton delocalization in conjugated polymer systems is determined by polymer conformations and packing. Since exciton delocalization determines the photoluminescent vibronic progression, optical spectroscopy provides an indirect link to polymer multiscale structures. This perspective describes our current theoretical understanding of how exciton delocalization in π-conjugated polymers determines their optical spectroscopy and further shows how exciton delocalization is related to conformational and environmental disorder. If the multiscale structures in conjugated polymer systems are known, then using first-principles modeling of excitonic processes it is possible to predict a wide-range of spectroscopic observables. We propose a reverse-engineering protocol of using these experimental observables in combination with theoretical and computational modeling to determine the multiscale polymers structures, thus establishing quantitative structure-function predictions.
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http://dx.doi.org/10.1063/1.4979495 | DOI Listing |
Adv Mater
January 2025
Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, China.
Hybrid excitons formed via resonant hybridization in 2D material heterostructures feature both large optical and electrical dipoles, providing a promising platform for many-body exciton physics and correlated electronic states. However, hybrid excitons at organic-inorganic interface combining the advantages of both Wannier-Mott and Frenkel excitons remain elusive. Here, hybrid excitons are reported in the copper phthalocyanine/molybdenum diselenide (CuPc/MoSe) heterostructure (HS) featuring strong molecular orientation dependence by low-temperature photoluminescence and absorption spectroscopy.
View Article and Find Full Text PDFSmall
January 2025
Department of Physics, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
In this study, we investigate how modulating organic spacers in perovskites influences their X-ray detection performance and reveal the mechanism of low-dose detection with high sensitivity using femtosecond-transient absorption spectroscopy (fs-TAS). Particularly, we employ N,N,N',N'-tetramethyl-1,4-phenylenediammonium (TMPDA) and N,N-dimethylphenylene-p-diammonium (DPDA) as organic spacers to synthesize 2D perovskite single crystals (SCs). We find that DPDA-based SCs exhibit reduced interplanar spacing between inorganic layers, leading to increased lattice packing.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.
Controlling charge transport at the interfaces of nanostructures is crucial for their successful use in optoelectronic and solar energy applications. Mixed-dimensional heterostructures based on single-walled carbon nanotubes (SWCNTs) and transition metal dichalcogenides (TMDCs) have demonstrated exceptionally long-lived charge-separated states. However, the factors that control the charge transport at these interfaces remain unclear.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry and Paula M. Trienens Institute for Sustainability and Energy Northwestern University, Evanston, Illinois 60208-3113, USA.
Organic donor-acceptor (D-A) cocrystals are gaining attention for their potential applications in optoelectronic devices. This study explores the dynamics of charge transfer (CT) and triplet exciton formation in various D-A cocrystals. By examining a series of D-A cocrystals composed of coronene (COR), peri-xanthenoxanthene (PXX), and perylene (PER) donors paired with N,N-bis(3'-pentyl)perylene-3,4:9,10-bis(dicarboximide) (PDI), naphthalene-1,4:5,8-tetracarboxy-dianhydride (NDA), or pyrene-4,5,9,10-tetraone (PTO) acceptors, using transient absorption microscopy and time-resolved electron paramagnetic resonance spectroscopy, we find that the strength of the CT interaction influences the nature and yield of triplet excitons produced by CT state recombination.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
Institute of Nano Science and Technology, Knowledge City, Sector 81, Manauli, Mohali, Punjab 140306, India.
Two-dimensional (2D) materials hold great promise for the next-generation optoelectronics applications, many of which, including solar cell, rely on the efficient dissociation of exciton into free charge carriers. However, photoexcitation in atomically thin 2D semiconductors typically produces exciton with a binding energy of ∼500 meV, an order of magnitude larger than thermal energy at room temperature. This inefficient exciton dissociation can limit the efficiency of photovoltaics.
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