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Non-covalent Interaction Controlled 2D Organic Semiconductor Films: Molecular Self-Assembly, Electronic and Optical Properties, and Electronic Devices
摘要： The establishment of electronic and opto-electronic products relying on organic semiconductors (OSCs) has been intensely explored over the past few decades due to their great competitiveness in large area, low cost, flexible, wearable and implantable devices. Many of these products already entered our daily lives, such as organic light-emitting diodes-based displays, portable organic solar cells and organic field-effect transistors. The device performance of OSC devices are determined by the supramolecular organization (orientation, morphology) as well as the supramolecular organization dependent energy level alignment at various interfaces (organic/electrode, organic/dielectric, organic/organic). This review focuses on the impact of non-covalent interaction on the molecular self-assembly of organic thin films, their electronic and optical properties, as well as the device performance. Beginning with the growth of multiple OSCs on substrates with different interfacial interaction strengths (metals, insulators, semiconductors), the critical roles of molecule-substrate and intermolecular interactions in determining the thin film organization have been demonstrated. Several non-covalent interactions that contribute to the energy levels of organic materials in solid phase are summarized, mainly including the induction contributions, electrostatic interactions, band dispersions and interface dipoles. The excitonic coupling in specific aggregations of organic molecules and the corresponded effect on their optical properties are also discussed. Finally, the influences of weak intermolecular interactions on the device performance are presented.
关键词： molecular self-assembly,optical properties,non-covalent interaction,electronic properties,electronic devices,organic semiconductors
更新于2025-09-23 15:19:57
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Conducting Polymers || Electrical Properties of Polymer Light-Emitting Devices
摘要： In this chapter, we present a brief introduction to semiconducting properties of conjugated polymers and the motivation to apply this class of materials in electronic/optoelectronic devices such as polymer light-emitting diodes (PLEDs). We describe, in detail, the operating mechanisms of PLEDs, with particular focus on the effects of charge injection and transport and their dependence on the external electric field and temperature. The mechanisms of current injection from the electrodes into the organic semiconductor are initially treated using traditional models for thermionic emission and tunnelling injection. More recent models considering the influence of metal/semiconductor interface recombination and of energetic and spatial disorder in the injection currents are also introduced and discussed. In addition, models considering space-charge-limited currents and trap-filling-limited currents are employed to describe the charge transport characteristics in the bulk. Furthermore, we present a brief discussion on ideas concerning the effects of the disorder on the charge-carrier transport behaviour.
关键词： space-charge-limited currents,conjugated polymers,polymer light-emitting diodes,organic semiconductors,electrical properties
更新于2025-09-19 17:15:36
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A quantitative structure–property study of reorganization energy for known p-type organic semiconductors
摘要： Intramolecular reorganization energy (RE), which quantifies the electron-phonon coupling strength, is an important charge transport parameter for the theoretical characterization of molecular organic semiconductors (OSCs). On a small scale, the accurate calculation of the RE is trivial; however, for large-scale screening, faster approaches are desirable. We investigate the structure–property relations and present a quantitative structure–property relationship study to facilitate the computation of RE from molecular structure. To this end, we generated a compound set of 171, which was derived from known p-type OSCs built from moieties such as acenes, thiophenes, and pentalenes. We show that simple structural descriptors such as the number of atoms, rings or rotatable bonds only weakly correlate with the RE. On the other hand, we show that regression models based on a more comprehensive representation of the molecules such as SMILES-based molecular signatures and geometry-based molecular transforms can predict the RE with a coefficient of determination of 0.7 and a mean absolute error of 40 meV in the library, in which the RE ranges from 76 to 480 meV. Our analysis indicates that a more extensive compound set for training is necessary for more predictive models.
关键词： molecular signatures,molecular transforms,reorganization energy,organic semiconductors,quantitative structure–property relationship
更新于2025-09-19 17:15:36
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Analysis of the charge transfer and separation in electrically doped organic semiconductors by electron spin resonance spectroscopy
摘要： We investigated the charge generation mechanism of electrically doped organic semiconductors (OSs) by electron spin resonance (ESR) analysis. ESR spectroscopy was used to successfully evaluate the radical density of p-doped OSs to estimate the charge transfer efficiency (CTE) of various doped systems. The results showed that the CTE is efficient close to 100% if the dopant molecules are homogenously dispersed and the energy difference (?E) between the highest occupied molecular orbital (HOMO) level of the host molecule and lowest unoccupied molecular orbital (LUMO) level of the p-dopant is large. The charge separation efficiency to form free carriers from the radicals is rather low (less than 12% in this study) and is a dominant factor controlling the charge generation efficiency (CGE). An organic dopant molybdenum tris[1,2-bis(trifluoromethyl)ethane-1,2-dithiolene] turns out to be an efficient dopant with the CGE of 9.7% due to high CTE originating from homogenous dispersion of the organic p-dopants and low LUMO level, i.e., large ?E.
关键词： charge generation efficiency,p-dopant,charge transfer,electron spin resonance spectroscopy,Organic semiconductors,charge separation
更新于2025-09-19 17:15:36
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New C–H Arylation Saves Steps for Small-Molecule Organic Semiconductors
摘要： New C–H Arylation Saves Steps for Small-Molecule Organic Semiconductors. Significance: Semiconductors based on organic molecules are appealing because of their applicability in the fabrication of various optoelectronic devices. They are particularly interesting because of their diverse molecular design, well-defined conjugation lengths, and easier modification of functional groups. In this report, Liu and co-workers developed a direct C–H (hetero)arylation reaction that enables the synthesis of semiconducting organic molecules by coupling various useful end groups to core-type building blocks in fewer steps. Comment: The authors optimized the reaction and investigated the scope in the synthesis of donor-type end groups, acceptor-type end groups, and various hybrid-type end groups. To demonstrate the utility of the reaction, they synthesized two new D–A–π-A′ organic sensitizers, CYL-3 and CYL-4 in fewer steps than is conventionally required. The dye-sensitized solar cells fabricated by using these organic sensitizers showed an impressive power conversion efficiency corresponding to 6.02% and 4.76%, respectively.
关键词： C–H arylation,organic semiconductors,thiophenes
更新于2025-09-19 17:15:36
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Theoretical study on the charge transport properties of three series dicyanomethylene quinoidal thiophene derivatives
摘要： It is very important to analyse the most advantageous connection style for quinoidal thiophene derivatives, which are used in n-type organic semiconductor transport materials. In the present work, the charge transport properties of three series of quinoidal thiophene derivatives, oligothiophene (series A), thienothiophene (series B) and benzothiophene (series C), are systematically investigated by employing the full quantum charge transfer theory combined with kinetic Monte-Carlo simulation. The single crystal structures of the molecules we constructed were predicted using the USPEX program combined with density functional theory (DFT) and considering the dispersion corrected. Our theoretical results expounded that how the different connection styles, including oligo-, thieno-, benzo- thiophene in the quinoidal thiophenes derivatives, effectively tune their electronic structures, and revealed that how their intermolecular interactions affect the molecular packing patterns and hence their charge transport properties by symmetry-adapted perturbation theory (SAPT). In the meanwhile we also elucidated the role of end-cyano groups in noncovalent interactions. Furthermore, it is clarified that the quinoidal thiophene derivatives show excellent carrier transport properties due to their optimal molecular stacking motifs and larger electronic couplings besides low energy gap. In addition, our theoretical results demonstrate that quinoidal oligothiophene derivatives (n=3~5) with more thiophene rings will have ambipolar transport properties, quinoidal thienothiophene and benzothiophene derivatives should be promising alternatives as n-type OSC. When we focused only on the electronic transport properties in the three series of molecules, quinoidal benzothiophene derivatives are slightly better than quinoidal oligothiophene and thienothiophene derivatives.
关键词： Crystal structure prediction,Dicyanomethylene quinoidal thiophene,N-type and ambipolar organic semiconductors,Charge transport property,Intermolecular interactions
更新于2025-09-19 17:15:36
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Converting an organic light-emitting diode from blue to white with Bragg modes
摘要： Organic light-emitting diodes (OLEDs) have been established as versatile light sources that allow for easy integration in large area surfaces and flexible substrates. In addition, the low fabrication cost of OLEDs renders them particularly attractive as general lighting sources. Current methods for the fabrication of white-light OLEDs rely on the combination of multiple organic emitters and/or the incorporation of multiple cavity modes in a thick active medium. These architectures introduce formidable challenges in both device design and performance improvements, namely the decrease of efficiency with increasing brightness (efficiency roll-off) and short operational lifetime. Here we demonstrate, for the first time, white light generation in an OLED consisting of a sub-100 nm-thick blue single emissive layer coupled to the photonic Bragg modes of a dielectric distributed Bragg reflector (DBR). We show that the Bragg modes, although primarily located inside the DBR stack, can significantly overlap with the emissive layer, thus efficiently enhancing emission and outcoupling of photons at selected wavelengths across the entire visible light spectrum. Moreover, we show that color temperature can be tuned by the DBR parameters, offering great versatility in the optimization of white-light emission spectra.
关键词： distributed Bragg reflector,white organic light-emitting diodes (WOLEDs),Fabry-Pérot modes,electroluminescence color conversion,organic semiconductors
更新于2025-09-19 17:13:59
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Effective design of novel low band gap acceptors for non-fullerene solar cells via modulating molecular planarity and F atom substitution
摘要： Due to the highly tunable molecular energy levels and potential for reducing synthesis costs, increased efforts have been devoted to developing non-fullerene acceptors. Herein we report two novel low band gap NF-SMAs for OSCs, namely IDBTC and IDBTCF. Thiophene-substituted benzothiadiazole is introduced between the donor and acceptor to regulate the coplanarity of the molecule and enhance intramolecular push-pull effect. In addition, the ?uorine atom was introduced into the benzothiadiazole to study the effect of ?uorination on the properties of NF-SMAs. As expected, they all exhibited good near infrared absorption and narrow band gap (Eopt < 1.6 ev). What’s more, the absorption spectrum is slightly enhanced and the energy level is shifted, by the introduction of ?uorine atoms into NF-SMAs. Furthermore, NF-SMAs were treated as acceptor and P3HT as donor in OSCs. The best device based on IDBTCF delivered a PCE of 3.22%. The PCE has increased from 2.5% (IDBTC) to 3.22% (IDBTCF) after introduction of ?uorine atoms. It indicates that the optical properties and electronic energy levels of NF-SMAs can be readily tuned by modulation of molecular planarity and the introduction of ?uorine atoms, which provides great opportunities for enhance the ef?ciency of OSCs.
关键词： Solar energy material,Organic,Semiconductors
更新于2025-09-19 17:13:59
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Recent Progress on Near-Infrared Photoacoustic Imaging: Imaging Modality and Organic Semiconducting Agents
摘要： Over the past few decades, the photoacoustic (PA) effect has been widely investigated, opening up diverse applications, such as photoacoustic spectroscopy, estimation of chemical energies, or point-of-care detection. Notably, photoacoustic imaging (PAI) has also been developed and has recently received considerable attention in bio-related or clinical imaging fields, as it now facilitates an imaging platform in the near-infrared (NIR) region by taking advantage of the significant advancement of exogenous imaging agents. The NIR PAI platform now paves the way for high-resolution, deep-tissue imaging, which is imperative for contemporary theragnosis, a combination of precise diagnosis and well-timed therapy. This review reports the recent progress on NIR PAI modality, as well as semiconducting contrast agents, and outlines the trend in current NIR imaging and provides further direction for the prospective development of PAI systems.
关键词： photoacoustic imaging,near-infrared,contrast agents,organic semiconductors
更新于2025-09-19 17:13:59
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Extending the Photovoltaic Response of Perovskite Solar Cells into the Near‐Infrared with a Narrow‐Bandgap Organic Semiconductor
摘要： Typical lead-based perovskites solar cells show an onset of photogeneration around 800 nm, leaving plenty of spectral loss in the near-infrared (NIR). Extending light absorption beyond 800 nm into the NIR should increase photocurrent generation and further improve photovoltaic efficiency of perovskite solar cells (PSCs). Here, a simple and facile approach is reported to incorporate a NIR-chromophore that is also a Lewis-base into perovskite absorbers to broaden their photoresponse and increase their photovoltaic efficiency. Compared with pristine PSCs without such an organic chromophore, these solar cells generate photocurrent in the NIR beyond the band edge of the perovskite active layer alone. Given the Lewis-basic nature of the organic semiconductor, its addition to the photoactive layer also effectively passivates perovskite defects. These films thus exhibit significantly reduced trap densities, enhanced hole and electron mobilities, and suppressed illumination-induced ion migration. As a consequence, perovskite solar cells with organic chromophore exhibit an enhanced efficiency of 21.6%, and substantively improved operational stability under continuous one-sun illumination. The results demonstrate the potential generalizability of directly incorporating a multifunctional organic semiconductor that both extends light absorption and passivates surface traps in perovskite active layers to yield highly efficient and stable NIR-harvesting PSCs.
关键词： narrow-bandgap organic semiconductors,perovskite solar cells,NIR light harvesting,passivation
更新于2025-09-19 17:13:59