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Recent advances in circularly polarized electroluminescence based on organic light-emitting diodes
摘要： Since the first attempt that was made to obtain direct circularly polarized (CP) light from OLEDs by Meijer et al. in 1997, considerable efforts have been devoted to the development of circularly polarized organic light-emitting diodes (CP-OLEDs), particularly in the recent years. Circularly polarized electroluminescence (CPEL) based on OLEDs has attracted increasing interest for its efficient ability to generate CP light directly and wide potential applications in 3D displays, optical data storage, and optical spintronics. In this review, we systematically summarize the recent progress in chiral emitter based OLEDs with CPEL properties including CPEL based on chiral conjugated polymers, CPEL based on chiral metal complexes, and CPEL based on chiral simple organic molecules, especially chiral thermally activated delayed fluorescence (TADF) molecules. We believe that this review will provide a promising perspective of chiral emitter based OLEDs with CPEL properties for a broad range of scientists in different disciplinary areas and attract a growing number of researchers to this fast-growing research field.
关键词： chiral simple organic molecules,circularly polarized electroluminescence,thermally activated delayed fluorescence,chiral conjugated polymers,organic light-emitting diodes,chiral metal complexes
更新于2025-09-16 10:30:52
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A Selfa??Assembled Small Moleculea??Based Hole Transporting Material for Inverted Perovskite Solar Cells
摘要： Hybrid organic-inorganic perovskite solar cells have recently emerged as one of the most promising low-cost photovoltaic technologies. The remarkable progress of perovskite photovoltaics is closely related to interfacial engineering and development of charge selective interlayers. Herein we present the synthesis and characterization of a fused azapolyheteroaromatic small molecule, namely anthradi-7-azaindole (ADAI), with outstanding performance as hole transporting layer in perovskite solar cells with inverted architecture. Its molecular arrangement, induced by hydrogen bond-directed self-assembly, favors a suitable morphology of layer, reducing recombination as revealed by light intensity dependence, photoluminescence and electroluminescence studies.
关键词： inverted perovskite solar cell,self-assembled conjugated molecule,undoped hole transport layer
更新于2025-09-16 10:30:52
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Modulation of Building Block Size in Conjugated Polymers with D–A Structure for Polymer Solar Cells
摘要： D?A conjugated polymers have played critical roles in recently reported nonfullerene acceptors-based polymer solar cells (NF-PSCs) with high performance. Although the molecular design of the D?A polymers is getting more mature, there are still some fundamental unknowns to be unveiled. Here, three new D?A polymers with varied conjugated length for the D-units in their backbones, namely, PDB-1, PDB-2, and PDB-3, were designed, synthesized, and characterized. It was demonstrated that a longer D-unit leads to stronger interchain interaction and higher hole mobility for pristine polymer films. While blending with IT-4F to fabricate photoactive layers in PSCs, it was found that the domain purity, aggregation size, and π?π stacking effect of the polymers can be greatly affected by the D-unit size. Compared to polymers with shorter D-units, for the polymer with the largest D-units (PDB-3), hole and electron transport channels can be much more easily formed in the blend films. Interestingly, the highest efficiency was obtained in the PSCs based on a PDB-2:IT-4F blend, in which PDB-2 shows similar D-unit size to the polymers with state-of-the-art high photovoltaic performance. The correlations between the molecular structure and photovoltaic property of PDB-x polymers demonstrate that the modulation of building block size is an important method for designing high-performance D?A conjugated polymers for PSCs.
关键词： polymer solar cells,nonfullerene acceptors,D?A conjugated polymers,building block size,photovoltaic performance
更新于2025-09-16 10:30:52
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Effect of Photocrosslinking of D‐A Thiophene Copolymers on the Performance of Single‐Material Solar Cells
摘要： Side-chain C60-fullerene functionalized alkylthiophene copolymers with different regioregularity and fullerene content are successfully synthesized using a simple and straightforward post-polymerization functionalization procedure based on a Grignard coupling reaction. The products are employed as single materials in photoactive layers of organic photovoltaic solar cells. The use of double-cable polymers allows an enhanced control on the nano-morphology of the active blend, reducing the phase-segregation phenomena as well as the macroscale separation between the electron acceptor and donor components. With the insertion of a thin layer of gold nanoparticles between buffer and active layer of the cells, a conversion efficiency of 5.68% is obtained. Moreover, an increased stability over time is achieved when the copolymers are photocrosslinked immediately after the annealing procedure, leading to acceptable efficiencies even after 80 h of accelerated ageing, a key feature for widespread applicability of the prepared devices.
关键词： conjugated polymers,metathesis,functionalization of polymers,fullerenes
更新于2025-09-12 10:27:22
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Wide-Band-Gap Phthalimide-Based D-π-A Polymers for Nonfullerene Organic Solar Cells: The Effect of Conjugated π-Bridge from Thiophene to Thieno[3,2- <i>b</i> ]thiophene
摘要： Conjugated polymers with D-π-A backbone structures have been intensively investigated and have largely promoted the rapid progress of organic solar cells (OSCs). However, as one of the simplest electron-accepting (A) units, phthalimide (PhI), only attracts less attention to construct promising D-π-A photovoltaic polymers in OSC community. Thus the correlations between the chemical structure-optoelectronic properties-photovoltaic performance need to be systematically investigated. Here, we combined the PhI moiety with the electron-donating (D) unit benzodithiophene (BDT) to synthesize two D-π-A copolymers PE80 and PE81, where the π-bridge corresponds to the thiophene (T) and thieno[3,2-b]thiophene (TT) respectively. When blended with a low bandgap (Eg=1.33 eV) non-fullerene acceptor Y6, PE81 achieved a power conversion efficiency (PCE) of 10.21% with an open circuit voltages (VOC) of 0.90 V, which are much higher than those of PE80:Y6 device (PCE = 4.11% and VOC = 0.88 V). Our results indicate that PhI is also a promising electron-deficient unit to construct photovoltaic polymers and using TT π-bridge is simple strategy to improve the photovoltaic performance of D-π-A polymers.
关键词： non-fullerene organic solar cells,D-π-A backbone,Conjugated polymers,thieno[3,2-b]thiophene,phthalimide
更新于2025-09-12 10:27:22
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D‐A Type Pendant Conjugated Molecules based on Triazine Center with Depressed Intramolecular Charge Transfer Characteristics as Gain Media for Organic Semiconductor Lasers
摘要： A set of fluorene-capped pendant conjugated molecules (T-m and T-p), which consist of triazine center with three carbazole substituents as the donor-acceptor (D-A) type pendant structure, were designed, synthesized and investigated as gain media for organic semiconductor lasers (OSLs). Particularly, varying the capping positions of the fluorene units onto the pendant core structures results in obviously different intramolecular charge transfer (ICT) properties, whereas T-m manifested depressed ICT characteristic and high fluorescence quantum yield. The lowest ASE threshold in neat films was recorded of 1.9 μJ/cm2 for T-m and 83.8 μJ/cm2 for T-p, respectively, which indicated that depressed ICT characteristic in the case of T-m helps to enhance the ASE properties. Remarkably, the ASE threshold remained almost unchanged and the ASE spectra showed very small shifts (within 1 nm) for T-m with film samples annealed up to 180°C in open air. In contrast, its linear counterpart 2FEtCz-m showed obviously increased ASE threshold upon annealing above 100°C. The results suggest that the selective construction of conjugated pendant molecules with depressed ICT characteristics is beneficial for finely modulating the optical and electrical properties as well as improving the thermostability and photostability, which manifests the great potentials as robust gain media for OSLs.
关键词： Organic semiconductors,Amplified spontaneous emission (ASE),Organic semiconductor lasers,Pendant conjugated molecules,Intramolecular charge transfer (ICT)
更新于2025-09-12 10:27:22
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Toward Scalable PbS Quantum Dot Solar Cells Using a Tailored Polymeric Hole Conductor
摘要： Colloidal quantum dot (CQD) solar cells processed from pre-exchanged lead sulfide (PbS) inks have received great attention in the development of scalable and stable photovoltaic devices. However, the current hole-transporting material (HTM) 1,2-ethanedithiol-treated PbS (PbS-EDT) CQDs have several drawbacks in terms of commercialization, including the need for oxidation and multilayer fabrication. Conjugated polymers are an alternative HTM with adjustable properties. Here we propose a series of conjugated polymers (PBDB-T, PBDB-T(Si), PBDB-T(S), PBDB-T(F)) for PbS CQD solar cells as HTMs. Through polymer side-chain engineering, we optimize the model polymer PBDB-T to tune the energy levels, increase hole mobility, improve solid-state ordering, and increase free carrier density. CQD solar cells based on modified polymer PBDB-T(F) exhibit a best power conversion efficiency (PCE) of 11.2%, which outperforms the devices based on conventional PbS-EDT HTM (10.6%) and is currently the highest PCE for PbS solar cells based on organic HTMs.
关键词： conjugated polymers,PbS,hole-transporting material,Colloidal quantum dot,power conversion efficiency,solar cells
更新于2025-09-12 10:27:22
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Conjugated Polymer-Quantum Dot Hybrid Materials for Pathogen Discrimination and Disinfection
摘要： In this work, a new platform for pathogen discrimination and killing based on a conjugated polymer-quantum dot hybrid material was designed and constructed through the fluorescence resonance energy transfer (FRET) process. The hybrid material comprises water-soluble anionic CdSe/ZnS quantum dots (QDs) and a cationic poly(fluorene-alt-phenylene) derivative (PFP) through electrostatic interactions, thus promoting efficient FRET between PFP and QDs. Upon addition of different pathogen strains, the FRET from PFP to QDs was interrupted because of the competitive binding between PFP and the pathogens. Complexation of PFP and QDs also reduced the dark toxicity to a more desirable level, therefore potentially realizing the controllable killing of pathogens. The technique provides a promising theranostic platform in pathogen discrimination and disinfection based on FRET and phototoxicity of the PFP and QDs.
关键词： FRET,pathogens discrimination and killing,quantum dots,conjugated polymers,theranostic platform
更新于2025-09-12 10:27:22
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Charge photogeneration and recombination in single-material organic solar cells and photodetectors based on conjugated star-shaped donor-acceptor oligomers
摘要： Single-material organic solar cells (SMOSC) are attracted by their simple structure and ease of fabrication so that they are virtually free from a number of drawbacks of heterojunction organic solar cells. However, the performance of SMOSC is still low, first of all because of poor understanding of losses on the way of energy conversion from light to electricity. In this work, we present solution-processed SMOSC based on star-shaped π-conjugated donor-acceptor oligomers with triphenylamine donor (N-Ph3) and alkyl- or phenyl dicyanovinyl acceptor (DCV-R) of general formulae N(Ph-nT-DCV-R)3, where nT stands for n-oligothiophene, and study charge photogeneration and recombination in them. SMOSC demonstrate small energy losses resulting in high open-circuit voltage of 1.08 – 1.19 V and the power conversion efficiency up to 1.22% under illumination intensity of 0.45 sun (1.13% under one sun) with the maximum external quantum efficiency up to 24% for N(Ph-2T-DCV-Ethyl)3, which are among the highest for SMOSC based on conjugated donor-acceptor small molecules or oligomers. It was found that monomolecular recombination dominates at the short-circuit condition and the maximum power point, but at the open-circuit condition the photoinduced charges recombine nearly bimolecularly. The bottleneck in the SMOSC performance was shown to be the field-assisted charge generation perfectly described by the Onsager model in the limit of weak electric fields. The results obtained suggest that intermolecular charge delocalization in conjugated donor-acceptor molecules would be beneficial for further progress in SMOSC.
关键词： conjugated molecule,charge recombination,donor-acceptor molecule,Onsager model,organic solar cell,charge generation
更新于2025-09-12 10:27:22
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Tuning the optoelectronic properties of oligothiophenes for solar cell applications by varying the number of cyano and fluoro substituents for solar cell applications: A theoretical study
摘要： Chemical modifications through substitution are observed to be effective in controlling the optoelectronic properties of various polymers for different applications. In this study, density functional theory–based calculations are employed to investigate the optoelectronic properties of several oligothiophenes based on poly(3-hexylthiophene-2,5-diyl) by varying the number of fluoro and cyano substituents attached. The resulting structures of the polymer derivatives are affected by the electrostatic interactions between the cyano or fluoro groups and the adjacent thiophene unit. Of the two, cyano substitution results in much lower frontier orbital energies for the same number of substituents. It was observed that a decrease in the highest occupied molecule orbital and lowest unoccupied molecular orbital energies correlates very strongly with the number of cyano and fluoro substituents. The effect of the cyano and fluoro groups on the frontier orbitals is also demonstrated and observed to correlate strongly with a lowering of the highest occupied molecule orbital and lowest unoccupied molecular orbital energies as the number of substituents is varied. The predicted solar cell characteristics reveal that most cyano and fluoro derivatives will have improved characteristics compared to unsubstituted poly(3-hexylthiophene-2,5-diyl). This theoretical study shows that by varying the number of electron-withdrawing substituents, the optoelectronic properties may be tuned for solar cell applications.
关键词： density functional theory,optoelectronic properties,organic solar cells,conjugated polymers,computational chemistry
更新于2025-09-12 10:27:22