The selective bis- and tris-functionalization of benzothioxanthene imides (BTI) with extended triphenylamine (eTPA) units, enabling precise tuning of optical and electronic properties, is introduced herein. Controlled bromination and subsequent Suzuki-Miyaura cross-coupling allow modular introduction of donor groups, resulting in redshifted emission into the red-near-infrared (NIR) region with large Stokes shifts and fluorescence quantum yield strongly modulated by solvent polarity and molecular environment. Photoemission measurements reveal HOMO stabilization upon addition of the third eTPA, illustrating the impact of subtle structural modifications on frontier orbital energies in the solid state. Both derivatives exhibit excellent film-forming and solvent-resistance properties, enabling, as an early proof of concept, their incorporation as emissive guests in solution-processed flexible organic light-emitting devices (OLEDs). Remarkably, while spectral variations were small, the third eTPA unit induces pronounced differences in device performance, illustrating how minimal and simple molecular modifications can deliver substantial functional gains.

Color conversion materials for next‐generation displays are fundamentally limited by architectures that rely on direct blue‐light absorption, requiring high‐emitter loading, thick films which often suffer from residual blue leakage, and instability. Here, we report a Förster resonance energy transfer (FRET)–dominated color conversion strategy based on surfactant‐stabilized organic nanocrystals (ONCs), in which nanoscale energy funneling, via resonant energy transfer, governs photon conversion efficiency rather than optical density. Binary color conversion films (CCFs) are constructed from blue‐emissive donor and green/red acceptor ONCs with precisely planned spectral overlap and nanoscopic proximity. This enables efficient FRET (70–80% efficiency and rate ≈8 × 108 s−1) that rapidly transfers energy from donors to acceptors prior to donor emission. The resulting mechanism effectively decouples blue absorption from emission, suppressing blue leakage and minimizing reabsorption losses. As a result, the ONC films achieve color conversion efficiencies of 85–90% and exhibit competitive performance relative to state‐of‐the‐art systems, with a lower concentration and thickness of 11–12 µm. These ONC films further preserve high color purity, enabling wide color gamuts of 88.76% BT.2020 and 112.2% NTSC, alongside excellent photostability under blue excitation. This work establishes FRET as a powerful design paradigm for ultra‐efficient, thin, and stable CCFs for display applications.

A critical factor affecting the efficiency of organic solar cells is the interfacial material between the electrode and the active layer. Developing interlayer systems whose electronic properties can be systematically tuned through simple compositional modification is attractive because it may enable more symmetric device architectures, simplified processing, and improved control of interfacial energetics. In this study, we prepared an interfacial control material by replacing p-doped poly(3,4-ethylenedioxythiophene) (PEDOT) in the well-known hole-transporting material (HTM) PEDOT:poly(styrenesulfonate) (PSS) with silver (Ag+ ions). Ag:PSS by itself was found to have insulating properties and did not yield compelling results as an HTM alone. However, we were able to control the polarity of Ag:PSS by mixing it with either PEDOT:PSS or poly(ethylenimine) (PEI), enabling its use as both HTM and electron transport material (ETM), respectively. By employing p-type and n-type Ag:PSS, we achieved power conversion efficiencies of up to 8.482% with a PTB7:PC71BM active layer. To analyze the effects on band structure, we used ultraviolet photoelectron spectroscopy (UPS) and inverse photoemission spectroscopy (IPES) to reveal systematic changes in energy bands that followed the interlayer composition. Our study demonstrates how compositional modification of Ag:PSS influences interfacial energetics and charge extraction behavior.

ABSTRACT Emerging applications such as brain‐machine interfaces, bio‐compatible prosthetics, and adaptive soft robotics rely on artificial neuromorphic devices that can interface directly with biological systems. To address this need, we demonstrate organic field‐effect transistors (OFETs) doped with a hybrid electrolyte, 1,4‐di‐ tert ‐butylbenzene‐2,5‐bis(1‐propoxy‐3‐sulfonate) lithium salt ( BBOPSO 3 Li ), as novel artificial synaptic devices. Incorporation of BBOPSO 3 Li into poly(3‐hexylthiophene) (P3HT) channels enables precise modulation of shallow trap states through the close energetic alignment of BBOPSO 3 Li with the P3HT HOMO (∼0.1 eV offset), resulting in tunable threshold voltage, controllable hysteresis, and enhanced carrier mobility. Doped devices exhibit outstanding synaptic functions, including excitatory postsynaptic current (EPSC), paired‐pulse facilitation (PPF), and long‐term potentiation–depression (PD) with analog weight updates. An optimal doping level of 0.070 mol% provides the highest excitability, balanced temporal memory characteristics, and the widest conductance window. System‐level validation demonstrated improved classification accuracy (up to 89.8% on MNIST‐like datasets) and robust time‐series prediction in a physical reservoir computing framework, achieving a normalized mean square error of −32 dB. These findings demonstrate that hybrid electrolytes capable of self‐doping can be used to introduce well‐defined, reversible trap states, allowing control of synaptic plasticity and temporal dynamics in OFETs, advancing their potential as efficient neuromorphic computing platforms.

Despite the versatile photophysical properties of quantum dots (QDs), the toxicity, potential health risks, and environmental impacts of widely used Cd or Pb-based QDs have motivated a search for QDs based on nontoxic alternatives. Indium phosphide (InP) QDs are one of the most promising types of III–V semiconducting nanocrystals due to the wide tunability of their emission wavelength and the non-toxicity of InP. Although InP QDs have desirable properties, it is difficult to achieve blue emission with pure InP QDs. Alloying with other elements to increase the bandgap is one approach to achieve blue emission. Ga is in the same group as In; GaP has a larger bandgap (2.27 eV) compared to InP (1.35 eV) but shares the same zinc blende crystal structure, so we explored the use of Ga as an alloying element in InP QDs. InGaP alloys have previously been reported in multi-step processes involving ion-exchange; in this work, we demonstrate the synthesis of InGaP QDs using a one-pot method using a stoichiometric excess of Ga, while limiting the amount of In in the reaction. InGaP cores were synthesized at different ratios of In to Ga and blue-shifts of absorption peaks were confirmed with increasing Ga content. After shell growth of high Ga-content cores, InGaP QDs showed sky-blue fluorescence, close to the blue emission necessary for display applications and blue-shifted compared to pure InP QDs. The photoluminescence quantum yield and full-width at half-maximum of the emission from InGaP QDs were 49.9

Abstract Achieving unipolar n-type transport in Y6-based organic field-effect transistors (OFETs) is challenging due to the intrinsic ambipolar nature of Y6, which leads to low on/off current ratios, high threshold voltages, and unreliable n-type operation. Here, we report a systematic study on polarity control of Y6 OFETs through direct doping with the ionic conjugated polymer PFN+Br-. Electrical characterization reveals a clear transition from ambipolar to unipolar n-type conduction, accompanied by a substantial enhancement in charge-carrier mobility, on/off current ratios (from ∼10 to 104), and reduced threshold voltages. Complementary spectroscopic analyses, including XPS, UPS, XAS, UV–Vis absorption, and GIWAXS, provide insight into the evolution of the electronic structure and microstructure with doping. At an optimal doping concentration of ∼15%, the Fermi level shifts towards the LUMO edge, leading to efficient electron injection and effective hole blocking, while maintaining favorable molecular ordering for charge transport. Excessive doping (>20%) induces structural disorder, increased trap density, and a recovery of ambipolar characteristics, resulting in performance degradation. This work establishes a clear structure-property relationship for doping in Y6-based OFETs and demonstrates ionic polymer doping as an effective strategy to achieve high-performance unipolar n-type organic transistors.

Light-emitting transistors (LETs) are emerging as a transformative class of optoelectronic devices that integrate light emission and switching functions within a single architecture, offering unique opportunities for next-generation displays, transparent electronics, and reducing the cost and complexity of display manufacture. Although significant progress has been made, advances in LETs remain fragmented across different material strategies and device designs. This short review addresses that gap by consolidating recent developments, spanning low-voltage hybrid architectures, high-color-purity quantum dot emitters, transparent electrodes, interfacial doping, and ambipolar charge injection. This consolidation provides a unified perspective that provides insight into the important role of charge-injection mechanisms in advanced LETs. By integrating these achievements and outlining future directions, this short review aims to provide both fundamental insights and practical guidance for advancing LET research toward real-world applications, including simplified displays, integrated photonics and opto-neuromorphic computing.

This study investigates the application of new hole transport layers (HTLs) integrating magnesium and palladium metals with the organic polymer poly(styrene sulfonate) (PSS) in organic solar cells (OSCs). When used alone, these HTLs exhibited various drawbacks; however, blending them with the benchmark material PEDOT:PSS mitigated these issues and improved efficiency. Ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) measurements provided a detailed understanding of the interfacial energy level alignment, electronic band structure, and band bending at the HTL/PTB7 interface. Single Mg:PSS and Pd:PSS OSCs showed efficiencies of 6.232 and 5.836%, respectively. The relatively low open-circuit voltage (VOC) and fill factor (FF) were attributed to Auger recombination under light intensity. UPS and XPS also indicated that the hole extraction capability of PTB7 was hindered, leading to recombination at the barrier. By blending with PEDOT:PSS, the efficiencies of Mg:PSS and Pd:PSS were improved to 8.356 and 8.303%, respectively. This improvement was due to reduced current leakage, resulting from higher shunt resistance and lower series resistance, as observed in dark current measurements. Additionally, the formation of ohmic contacts at the HTL/PTB7 interface enhanced hole extraction and reduced recombination. This study underscores the potential of mixed organic-metal HTL structures in OSCs to modulate energy band structures, providing insights into the selection of metal-organic combinations for optimizing OSC efficiency and performance.

ABSTRACT Polymer dielectric‐based organic field‐effect transistors (OFETs) have attracted significant attention due to their potential applications in transparent and flexible electronics, intelligent labels for smart packaging, and chemical and biosensors. Herein, we demonstrate OFETs incorporating poly(chloro‐p‐xylylene) (parylene‐C) as the gate dielectric with variable thickness in the range of 250–450 nm in 50 nm increments, with careful investigation of their electrical characteristics. The results showed that an optimal dielectric thickness of parylene‐C (350 nm) significantly enhanced device performance compared to a standard SiO 2 dielectric, achieving a low threshold voltage (V Th ) (0.23 V), a higher on/off ratio (I on/off ) (7.27 × 10 3 ), and increased hole mobility (µ h ) (1.29 × 10 −2 cm 2 V −1 s −1 ). To understand how the thickness of the parylene‐C dielectric layer influences the performance of OFETs, a variety of analyses were conducted, including capacitance‐voltage and water contact angle measurements, atomic force microscopy, and grazing incidence wide‐angle X‐ray scattering. Furthermore, X‐ray absorption spectroscopy was employed to analyze the electronic structure and molecular orientation of parylene‐C and the PBTTT‐C14 layer deposited on it. This study offers valuable insights for optimizing OFETs with parylene‐C dielectric layers, paving the way for the development of next‐generation flexible and low‐power electronic devices.

This study explores the synthesis of water-based color-tunable organic nanodots (CTONDs) capable of emitting multiple colors, including white light, by adjusting the molar ratio of blue, green, and red emissive fluorophores in the particles. Spectroscopic analyses reveal that the emissions are due to Forster resonance energy transfer (FRET) between the energy donor and acceptor nanoparticles. The energy transfer efficiencies are high, reaching over 90% in the film state due to the close packing of NDs while in their film state. Various molar ratios produced different colors in both liquid dispersions and in the solid state. These CTONDs demonstrate over 60% color conversion efficiency (CCE) when applied as color conversion layers (CCLs) in light-emitting devices, maintaining photostability for over four months under ambient conditions. Additionally, their aqueous processability and multicolor tunability make them attractive for environmentally friendly display technologies, flexible optoelectronics, and anti-counterfeiting applications such as security inks. This work offers a scalable and sustainable approach to fabricating tunable, solution-processed fluorescent organic nanomaterials and underscores their promise as a versatile platform for next-generation photonic and optoelectronic applications.

Electronic noses (E-noses) mimic olfactory organs and detect volatile organic compounds (VOCs) for applications in environmental monitoring, healthcare, and food safety. Organic field-effect transistor (OFET) sensors offer an economical platform for large-scale production, but their selectivity remains a challenge. In this study, we incorporate semi-permeable polymer membranes into OFET vapor sensors to enhance analyte differentiation. Acylated poly(vinyl alcohol) (PVA) derivatives were synthesized, characterized, and applied as selective membranes. By monitoring drain current over time, we demonstrated that these membranes significantly improved sensor selectivity, particularly in distinguishing similar VOCs such as methanol and ethanol. This strategy enables cost-effective fabrication of highly selective organic vapor sensors by modulating membrane properties.

A highly stable molecular radical cation (RC) derived from ethylenedioxy thiophene (EDOT) is effectively utilized for the p-doping of poly-3-hexylthiophene (P3HT), an organic semiconductor. The success of this process is due to efficient electron transfer from the highest occupied molecular orbital band of P3HT to the singly unoccupied molecular orbital of the radical cation species. Confirmation of the doping is experimentally confirmed through UV-vis-NIR absorption spectroscopy and electron spin resonance spectroscopy. The ability to dope the conjugated polymers PBTTT and PTB7 is also spectroscopically confirmed. An increase in work-function of P3HT upon doping is observed due to electron transfer from P3HT to the radical cation with a concomitant decrease in the Fermi energy of P3HT. Impedance and four point probe analysis showed that the doped polymer films exhibited a significant decrease in resistance compared to the pristine films. This work presents the first use of a stable, easily synthesized EDOT-based radical cation as a molecular p-dopant for conjugated polymers, offering a novel and broadly applicable alternative to traditional dopants such as F4TCNQ.

This work investigates the role of metal ion-doped (Cs+, Ni2+, and Cu2+) PEDOT:PSS films as hole transport layers (HTLs) in quasi-2D perovskite light-emitting diodes (PeLEDs). These HTLs lead to enhanced device performance through reduced defect density, improved hole mobility, and prolonged photoluminescence lifetime. X-ray diffraction (XRD) reveals structural modifications in CsPbBr3 films, with enhanced crystallinity resulting from the elimination of excess long-chain cations. Morphological analyses using scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate the influence of metal doping on surface coverage and nanoscale roughness. Time-resolved photoluminescence (TR-PL) analysis confirms reduced nonradiative recombination, supporting improved film quality. Devices with Ni:PEDOT:PSS exhibit the highest external quantum efficiency, while Cs:PEDOT:PSS and Cu:PEDOT:PSS offer enhanced stability, achieving significantly longer operational lifetimes. These findings highlight the potential of metal-doped PEDOT:PSS in optimizing the structural, optical, and electrical properties of perovskite materials, paving the way for more stable and efficient PeLEDs.

Electronic noses (E-noses) mimic olfactory organs and quantify volatile organic compounds (VOCs), emulating the sense of smell, with applications in real-time monitoring of VOCs in food, healthcare, and law enforcement industries. Organic field-effect transistor (OFET) based sensors can be fabricated in large arrays by economical processes, however, lack the selectivity necessary to differentiate wide varieties of VOCs. Here, we explore the use of permeable polymer membranes with OFET sensors to improve their selectivity. Acylated poly(vinyl alcohol) (PVA) derivatives were synthesized, characterized, and evaluated in OFET vapor sensors as tunable membranes. Sensors with and without acylated PVA membranes were tested with VOC analytes. By monitoring drain current over time, we found that membranes dramatically changed responses to different analytes. We show that VOCs including methanol, ethanol, hexane, toluene, tetrahydrofuran, methyl ethyl ketone, and ethyl acetate can all be detected and differentiated with much greater selectivity than sensors without membranes. In particular, methanol and ethanol, which are difficult to differentiate in vapor sensors, showed significant quantitative differences in the initial slope (0.0403 s−1 vs 0.0192 s−1 respectively; 6 σ) and decay constants (5.5 s vs 15.9 s respectively; 26 σ) of their current vs time responses, allowing methanol and ethanol to be differentiated with 100 % confidence. This approach enables the economical fabrication of large varieties of unique organic vapor sensors by simply changing the membrane layer and results in an outstanding level of selectivity for OFET vapor sensors.

Engineering interfacial materials for use between the active layer and the electrodes in organic and perovskite solar cells is one of the most effective ways to increase device efficiency. Despite decades of development, new materials continue to emerge offering improved performance and streamlined fabrication of devices. Here, a hole transport layer (HTL) for organic and perovskite solar cells combining poly(styrene sulfonate) (PSS) and nickel (Ni2+) is presented. P-type carriers and p-doping at the anode are stabilized by the PSS backbone's negatively charged state. The impact of ionic moieties on the electronic band structure and characteristics of organic and perovskite solar cells must be understood. The combination of Nickel(ii): poly(styrene sulfonate) (Ni:PSS) and poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) can improve efficiency to 15.67% (perovskite solar cell) and 16.90% (organic solar cell) over traditional Ni:PSS and PEDOT:PSS. Ultraviolet photoelectron spectroscopic observations at HTL/donor interfaces indicate energy level alignment, which is the cause of various changes in device performance. Low ionization potential (IP) and hole injection barrier (phi h) are essential at the HTL/donor interface for effective charge extraction in organic and perovskite solar cells. Engineering interfacial materials for use between the active layer and the electrodes in organic and perovskite solar cells is one of the most effective ways to increase device efficiency.

Growing concern about climate change has spurred the rapid development of alternative energy sources; however, the lack of infrastructure required to store and distribute energy from such intermittent sources hinders their large-scale implementation. Redox flow batteries (RFBs) offer an excellent solution to this problem; however, the development of active materials with higher energy densities and stabilities is necessary. In this contribution, we explore the use of the 3,4-ethylenedioxythiophene (EDOT) moiety, an imminently useful p-type moiety in the context of organic semiconductors, as a radical cation carrying redox active molecule in RFBs. The 2,5-bis-t-butyl derivative of EDOT, t-Bu2EDOT, was synthesized and characterized; analysis by quantum chemical calculations, cyclic voltammetry, and spectroscopic analysis indicates that it exhibits higher oxidation potential and potentially greater stability than the current state of the art benzene-based reference material, 1,4-di-tert-butyl-2,5-bis(2-methoxyethoxy)benzene (DBBB). Functioning hybrid RFBs were constructed and higher operating voltages and charge capacity were confirmed compared to those with DBBB. The molar solubility was measured to be 183% for DBBB, while the operating voltage was 150 mV higher, indicating potential for 90% greater energy density using t-Bu2EDOT, compared to DBBB. The theoretical energy density of t-Bu2EDOT (41 905 mA h L-1) based on these values is much higher than that of DBBB (21 967 mA h L-1).

Light-emitting transistors (LETs) are a remarkable, emerging class of electronic devices that combine the switching function of field-effect transistors (FETs) and the light-emitting function of light-emitting diodes (LEDs). In order to achieve efficient light emission, effective electron and hole injection from source and drain electrodes is necessary. Various strategies have been introduced to accomplish this, such as incorporating asymmetric electrodes or charge injection layers during device fabrication. These approaches have inevitably introduced complexity in the device fabrication process. Herein, light-emitting electrochemical transistors (LECTs) are demonstrated that combine principles of electrochemistry and optoelectronics to achieve multi-functionality in a simple device architecture. Hybrid polyelectrolytes, poly(9-vinylcarbazolesulfonate)- lithium and copper (II) salts (PVK-Li and PVK-Cu) incorporating Li+ ion and Cu2+ ions are added at variable concentrations to the organic emitting layer of LECTs to effect electrochemical p-type doping. This electrochemical doping approach yielded improvements in electrical and optical performances including mobilities, brightnesses, and external quantum efficiency of the LECTs. The dynamics of how charges including ions, electrons, and holes move and interact are discussed in the device to facilitate emissive charge carrier recombination and light emission. This investigation provides valuable insights into the realms of both electrochemistry and optoelectronics. Light-emitting electrochemical transistors (LECTs) are demonstrated, which integrate the principles of electrochemistry and optoelectronics to achieve multifunctionality within a simple device architecture. An electrochemical redox process is made possible by sulfonated poly(9-vinylcarbazole) polyelectrolyte Li+ and Cu2+ salts (PVK-Li and PVK-Cu) near the source and drain electrodes. Efficient electron and hole injection through an electrochemical doping process is observed under sufficient bias. image

Controlling the formation of photoexcited triplet states is critical for many (photo)chemical and physical applications. Here, we demonstrate that a permanent out-of-plane distortion of the benzothioxanthene imide (BTI) dye promotes intersystem crossing by increasing spin-orbit coupling. This manipulation was achieved through a subtle chemical modification, specifically the bay-area methylation. Consequently, this simple yet efficient approach expands the catalog of known molecular engineering strategies for synthesizing heavy atom-free, dual redox-active, yet still emissive and synthetically accessible photosensitizers.

Research in the field of organic electronics has witnessed dramatic improvements in device performance over the past several decades through an ever-improving understanding of electron and hole movement and the development of new interfacial materials. In this study, a type of interfacial material that relies on ionic charges comprising metal:poly(styrenesulfonate) (PSS) polyelectrolytes are synthesized and investigated as structural analogs of the ubiquitously used poly(3,4-ethylenedioxythiophene:polystyrenesulfonate) (PEDOT:PSS) hole transport layer, in order to investigate correlations between metal cation ions and the cationic PEDOT component. The metal ions selected for this study include Li, Mg, V, Mn, Co, Ni, Cu, Zn, Pd, Ag, Cs, and Pb ions. To analyze the interfacial energy level alignment, electronic band structure, and band bending at the Indium tin oxide (ITO)/metal:PSS interface, X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) are employed. Alkali (earth) and post-transition metals show deep highest occupied molecular orbital (HOMO) levels and low work function (WF) due to Fermi level balance, implying poor hole transport. Remarkably, Cu:PSS displays a unique electronic structure, suggesting potential as a hole transport layer with increased WF and low hole injection barrier. Period 5 transition metals mirror PEDOT:PSS trends, and Ag:PSS holds the potential to form effective ohmic contacts. In this study, metal:poly(styrenesulfonate) (PSS) polyelectrolytes with metal cations including Li, Mg, V, Mn, Co, Ni, Cu, Zn, Pd, Ag, Cs, and Pb, are studied using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The interfacial energy level alignment, electronic band structure, and band bending at the ITO/metal:PSS interface are characterized.image