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Triplet acceptors with Da??A structure and twisted conformation for efficient organic solar cells
摘要： Triplet acceptors have been developed to construct high performance organic solar cells (OSCs) since the long lifetime and diffusion range of triplet excitons may dissociate into free charges instead of net recombination when the energy levels of triplet states (T1) are close to those of charge transfer states (3CT). The current triplet acceptors were designed by introducing heavy atoms to enhance the intersystem crossing, limiting their applications. Herein, two twisted acceptors without heavy atoms, analogues of Y6, were constructed with large π-conjugated core and D-A structure, proved to be triplet materials, leading to a high performance OSCs. The mechanism of triplet excitons were investigated to show that the twisted and D-A structures result in large spin orbital coupling (SOC) and small energy gap between the singlet and triplet states, and thus efficient intersystem crossing. Moreover, the energy level of T1 is close to 3CT, facilitating the split of triplet exciton to free charges. This contribution provided new insights in working mechanism of triplet excitons in OSCs.
关键词： twisted conformation,D-A structure,long lifetime exciton,triplet acceptor,organic solar cells
更新于2025-09-23 15:21:01
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Opportunities and challenges of interlayer exciton control and manipulation
摘要： Advances in van der Waals heterostructures allow the control of interlayer excitons by electrical and other means, promising exciting opportunities for high-temperature exciton condensation and valley–spin optoelectronics.
关键词： TMD bilayers,exciton condensation,van der Waals heterostructures,valley–spin optoelectronics,interlayer excitons
更新于2025-09-23 15:21:01
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AIP Conference Proceedings [AIP Publishing 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Bikaner, India (14a??15 October 2019)] 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Study of optical properties of Wannier-Mott exciton in spherical quantum dot in Kratzer potential
摘要： Study of optical properties of Wannier-Mott exciton in spherical quantum dot in Kratzer potential
关键词： Kratzer potential,spherical quantum dot,Wannier-Mott exciton,optical properties
更新于2025-09-23 15:21:01
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Understanding degradation of organic light-emitting diodes from magnetic field effects
摘要： The impact of magnetic field effects on the electroluminescence of organic light-emitting diodes is commonly used to characterize exciton dynamics such as generation, annihilation, and performance degradation. However, interpreting these effects is challenging. Here, we show that magnetic field effects in organic light-emitting diodes can be understood in terms of the magnetic response of device characteristics derived from polaron-pair and triplet exciton quenching processes, such as triplet-polaron interactions and triplet-triplet annihilation. Device degradation shows a clear relationship with the amplitude of the magnetic field effects, enabling non-destructive measurement of the degradation. The results and proposed mechanism provide a better understanding of magnetic field effects on organic light-emitting diodes and device degradation phenomena.
关键词： magnetic field effects,device degradation,organic light-emitting diodes,triplet-polaron interactions,triplet-triplet annihilation,exciton dynamics
更新于2025-09-23 15:21:01
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Recent Progress of Strong Exciton-Photon Coupling in Lead Halide Perovskites
摘要： The semiconductor exciton–polariton, arising from the strong coupling between excitons and confined cavity photon modes, is not only of fundamental importance in macroscopic quantum effects but also has wide application prospects in ultralow-threshold polariton lasers, slowing-light devices, and quantum light sources. Very recently, metallic halide perovskites have been considered as a great candidate for exciton–polariton devices owing to their low-cost fabrication, large exciton oscillator strength, and binding energy. Herein, the latest progress in exciton–polaritons and polariton lasers of perovskites are reviewed. Polaritons in planar and nanowires Fabry–Pérot microcavities are discussed with particular reference to material and photophysics. Finally, a perspective on the remaining challenges in perovskite polaritons research is given.
关键词： exciton–polariton,low threshold laser,lead halide perovskite,optical microcavity,strong light–matter interaction
更新于2025-09-23 15:21:01
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The Balance between Energy Transfer and Exciton Separation in Ternary Organic Solar Cells with Two Conjugated Polymer Donor
摘要： Ternary strategy as a straightforward way for organic solar cells (OSCs) to improve the device performance attracts many interests in the field. The ternary strategy usually focuses on processing the third light-absorbing material owning a complementary absorption to the binary system. However, studying the third component with similar absorption spectra to the binary counterpart is equally essential to understand the in-depth mechanism of the performance improvement from the third component. In this work, we filled up this blank and derived a type of ternary device consisting of two conjugated polymer donor materials of PTB7-Th and PffBT4T-2OD and non-fullerene acceptor material of IEICO-4F. The average PCE value of the optimized ternary device reached 12.1%, which is around 16% higher than its PTB7-Th:IEICO-4F binary counterpart. Even the third component of PffBT4T-2OD containing a similar absorption spectrum with PTB7-Th, it was found that the Jsc increase contributes to the primary performance enhancement. Further investigations indicate that the Jsc increase in the optimized ternary device mainly came from the improved light absorption ability, current extraction process, charge transport process, and suppressed non-radiative recombination. Moreover, there is a balance found between the exciton separation process and the energy transfer process when optimizing ternary blend ratios. The optimized ternary device is suspected to reach this balance point and thus exhibits the enhancement in device performance. Morphology investigation reveals that the addition of PffBT4T-2OD can tune the morphology and increase the crystallinity in the active layer. The optimized ternary blend shows a well-mixed donor and acceptor morphology with small domain size and slightly increased crystallization, which further explained its best device performance.
关键词： non-fullerene,energy transfer,exciton separation,organic solar cells,ternary,crystallization,conjugated polymer
更新于2025-09-23 15:21:01
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Strategically Modulating Carriers and Excitons for Efficient and Stable Ultrapurea??Green Fluorescent OLEDs with a Sterically Hindered BODIPY Dopant
摘要： Ultrapure colors are vital for displays to obtain the highly desired wide color-gamut. Till now, only boron-dipyrromethene derivatives (BODIPYs) have demonstrated ultrapure full-colors but suffer from low excitons utilization efficiency as dopants in organic light-emitting diodes. It is proposed here that with a thermally activated delayed fluorophore to sensitize BODIPYs, all excitons can be recycled, which, still, is challenged by exciton loss through Dexter energy transfer (DET) from sensitizer to dopant and direct charge trapping on BODIPYs. Hence, a sterically hindered BODIPY-type dopant with a bulk substituent on the meso-position is developed to suppress DET, exhibiting a high photo-luminance quantum yield of 98% and a small full width at half maximum of 28 nm. Moreover, the device structure is elaborately designed, successfully modulating carriers and excitons to avoid charge trapping on dopant and also trigger multiple-sensitizing processes to reduce exciton loss. Consequently, a state-of-the-art maximum external quantum efficiency/power efficiency of 19.0%/85.7 lm W?1 are realized together with an ultrapure-green emission of Commission Internationale de l’Eclairage coordinates of (0.26, 0.67) and a long half-lifetime of 2947 h at an initial luminance of 1000 cd m?2.
关键词： carrier modulation,ultrapure green emission,exciton modulation,high-efficiency devices,fluorescent organic light-emitting diodes,long-lifetime devices
更新于2025-09-23 15:21:01
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An inverted BiI3/PCBM binary quasi-bulk heterojunction solar cell with a power conversion efficiency of 1.50%
摘要： The use of toxic Pb hinders the widespread applications of lead halide perovskite solar cells, sparking an upsurge effort to develop lead-free solar cells. This work reports a facile low-temperature solution processed bismuth triiodide (BiI3)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) binary quasi-bulk heterojunction (BQ-BH) solar cell. The BiI3 and PCBM layers are innovatively utilized as the electron donor and acceptor to form a BQ-BH that promotes the separation of the excitons. The effective separation of excitons at the BiI3/PCBM BQ-BH is experimentally confirmed by the Kelvin probe force microscopy. An optimized inverted BiI3/PCBM BQ-BH solar cell can achieve a champion power conversion efficiency of 1.50% with a record short-circuit current density of 8.76 mA cm-2. The findings of this work confirm that the separation of excitons can be effectively promoted by inducing a suitable electron donor/acceptor type of BQ-BH, providing a new means to enhance the performance of BiI3-based solar cells.
关键词： electron acceptor,quasi-bulk heterojunction,exciton separation,solar cells,BiI3
更新于2025-09-23 15:21:01
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Robust and Fragile Quantum Effects in the Transfer Kinetics of Delocalized Excitons between B850 Units of LH2 Complexes
摘要： Aggregates of light harvesting 2 (LH2) complexes form the major exciton-relaying domain in the photosynthetic unit of purple bacteria. Application of a generalized master equation to pairs of the B850 units of LH2 complexes, where excitons predominantly reside, provides quantitative information on how the inter-LH2 exciton transfer depends on the distance, relative rotational angle, and the relative energies of the two LH2s. The distance dependence demonstrates significant enhancement of the rate due to quantum delocalization of excitons, the qualitative nature of which remains robust against the disorder. The angle dependence reflects isotropic nature of exciton transfer, which remains similar for the ensemble of disorder. The variation of the rate on relative excitation energies of LH2 exhibits resonance peaks, which, however, is fragile as the disorder becomes significant. Overall, the average transfer times between two LH2s are estimated to be in the range of 4?25 ps for physically plausible inter-LH2 distances.
关键词： light harvesting 2 (LH2) complexes,quantum delocalization,exciton transfer,photosynthetic unit,purple bacteria,disorder
更新于2025-09-23 15:21:01
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Strong Exciton-Plasmon Coupling and Hybridization of Organic-Inorganic Exciton-Polaritons in Plasmonic Nanocavity <sup>*</sup>
摘要： We investigate strong exciton-plasmon coupling and plasmon-mediated hybridization between the Frenkel (F) and Wannier–Mott (WM) excitons of an organic-inorganic hybrid system consisting of a silver ring separated from a monolayer WS2 by J-aggregates. The extinction spectra of the hybrid system calculated by employing the coupled oscillator model are consistent with the results simulated by the finite-difference time-domain method. The calculation results show that strong couplings among F excitons, WM excitons, and localized surface plasmon resonances (LSPRs) lead to the appearance of three plexciton branches in the extinction spectra. The weighting efficiencies of the F exciton, WM exciton and LSPR modes in three plexciton branches are used to analyze the exciton-polaritons in the system. Furthermore, the strong coupling between two different excitons and LSPRs is manipulated by tuning F or WM exciton resonances.
关键词： coupled oscillator model,finite-difference time-domain method,localized surface plasmon resonances,plasmonic nanocavity,exciton-plasmon coupling,Frenkel excitons,organic-inorganic hybrid system,Wannier–Mott excitons
更新于2025-09-23 15:21:01