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The fabrication and characterization of an all polymers‐based bulk heterojunction type organic photodiode having a narrowband response in the near‐infrared spectral region with full width at half‐maxima of 63 nm is reported. The active layer of the photodiode constitutes a 1:1 (by weight) blend of poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b']dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] (PCE10) and poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diy1]‐alt‐5,5′‐(2,2′‐dithiophene)} (N2200) deposited using solution processing. The device exhibits a linear dynamic range of 35 dB, response speed of 893 kHz, and specific‐detectivity of 109 Jones at 808 nm excitation wavelength. The narrowband response is achieved using the charge collection narrowing mechanism in a 2.7 μm thick junction device. [ABSTRACT FROM AUTHOR]

Excited‐state intramolecular proton transfer (ESIPT) chromophores have attracted considerable attention as promising gain media for organic lasers, particularly in amplified spontaneous emission (ASE) due to their advantageous characteristics. These include an intrinsic four‐level photocycle, significant separation between absorption and emission spectra, and enhanced emission efficiency facilitated by aggregate‐induced emission. This study investigates the amplification of π‐conjugation in hydroxyphenyl‐benzothiazole (HBT)‐based ESIPT materials via dimerization to intensify ESIPT processes, surge absorption cross‐section, enhance optical gain, and induce a redshift in emission spectra. Computational study shows that the ESIPT processes of the new dimers proceed through single proton transfer where the second proton transfer is not accessible. While the ESIPT photocycle does not extend to both HBT moieties of the dimers, the dimers foster more efficient ESIPT processes in both solution and solid states than their parent HBT, resulting in substantial Stokes shifts (>233 nm). Moreover, both dimers exhibit enhanced solid‐state photoluminescence quantum yields, reaching up to ≈55%, and low solid‐state ASE threshold values (≈6.8 µJ cm−2) in the red region. Remarkably, the new dimers demonstrate excellent thermal and photostability with notably reduced spectral overlap compared to their parent, highlighting the potential utility of the approaches to developing new organic solid‐state laser materials. [ABSTRACT FROM AUTHOR]

Chromophores undergoing excited‐state intramolecular proton transfer (ESIPT) feature a distinct four‐level photocycle and significant Stokes shift, which make them ideal for achieving population inversion upon photoexcitation, a fundamental prerequisite for lasing, by mitigating the concerns of self‐absorption owing to spectral overlap. This study focuses on functionalizing the hydroxyphenyl‐benzothiazole (HBT) ESIPT laser dye through the introduction of fluorene and phenyl‐carbazole moieties at the para‐position to the hydroxyl group, to demonstrate amplified spontaneous emission (ASE) activities. The synthesized HBT derivatives not only exhibit high thermal and photostability, but also high photoluminescence quantum yields, exceeding 40%, which is noteworthy for ESIPT materials emitting in the yellow–orange to red color ranges. Computational analyses show that these new HBT materials possess substantially lower ESIPT energy barriers, compared to their parent HBT, facilitating their efficient ESIPT processes. Moreover, these derivatives demonstrate a high radiative rate of 1.47 × 108 s−1. Thin films of a fluorene‐substituted HBT (HBT‐pFl) show a low solid‐state amplified spontaneous emission threshold value of 3.8 µJ cm−2 at 582 nm, representing the lowest reported solid‐state ASE threshold for laser dyes in the orange emission region (575–600 nm) to date. [ABSTRACT FROM AUTHOR]

Different approaches have been introduced to raise the response speed of bulk heterojunction‐based organic photodiodes (OPDs), with the best‐performing devices now having speeds in the MHz range. In most organic photodiodes, the response speed is commonly assumed to be due to transit time of charge carriers. Upon investigating fluence‐dependent photoresponse of different OPDs, it is found here that bimolecular recombination dictates the response speed at higher fluence levels. Herein, four different organic blend based photodiode systems and their response speed to a range of incident optical fluences are reported. A steep variation in response speed, depending upon the blend system is observed. Using experimental and theoretical studies, the intensity‐dependent response speeds are attributed to differences in the suppressed recombination factor. A high factor enables faster response times in the regime of higher light intensity. This new approach to high‐speed detections has implications for the design of high‐speed organic photodetectors, especially in applications where the speed of the photodetector is most important irrespective of the intensity of the incident signal. [ABSTRACT FROM AUTHOR]

The facile oxidation of Sn2+ to Sn4+ poses an inherent challenge that limits the efficiency and stability of tin‐lead mixed (Sn−Pb) perovskite solar cells (PSCs) and all‐perovskite tandem devices. In this work, we discover the sustainable redox reactions enabling self‐healing Sn−Pb perovskites, where their intractable oxidation degradation can be recovered to their original state under light soaking. Quantitative and operando spectroscopies are used to investigate the redox chemistry, revealing that metallic Pb0 from the photolysis of perovskite reacts with Sn4+ to regenerate Pb2+ and Sn2+ spontaneously. Given the sluggish redox reaction kinetics, V3+/V2+ ionic pair is designed as an effective redox shuttle to accelerate the recovery of Sn−Pb perovskites from oxidation. The target Sn−Pb PSCs enabled by V3+/V2+ ionic pair deliver an improved power conversion efficiency (PCE) of 21.22 % and excellent device lifespan, retaining nearly 90 % of its initial PCE after maximum power point tracking under light for 1,000 hours. [ABSTRACT FROM AUTHOR]

Organic laser materials are compared based on their ability to exhibit amplified spontaneous emission (ASE) and the energy threshold (E ASEth) required to achieve it. Very broadly, ASE demonstrates whether energy gains exceed energy losses within a given system. Various material design strategies have been explored to maximise gains and minimise losses. Among these, excited state intramolecular proton transfer (ESIPT) materials enable the absorbing species to differ greatly from the emitting species through enol–keto tautomerisation, generating a substantial Stokes shift and eliminating self-absorption losses. However, the resulting large Stokes shift also makes the development of efficient blue-emitting ESIPT laser semiconductors challenging. This work leveraged a combinatorial design strategy in ESIPT while simultaneously endowing molecular rigidity through strategic placement of one or two bonds to increase the rigidity of the chromophore for constrained non-radiative decay pathways. As a result, uncharacteristically high intrinsic photoluminescence quantum yields of 33–55% are observed for these new ESIPT chromophores. They are also found to exhibit high solid-state PLQYs (34–49%) in the blue region. These new chromophores further facilitated low solid-state ASE thresholds (4.4–5.2 μJ cm−2 at 6 wt% in a common host material, 4,4′-bis(N-carbazolyl)-1,1′-biphenyl). Thus, even without a resonating structure, all compounds outperformed the literature parent HPI-Ac single crystals with a laser threshold of 6.0 μJ cm−2, showing the benefits of a rigidity approach to low solid-state ASE thresholds for blue ESIPT laser chromophores. [ABSTRACT FROM AUTHOR]

Photodetectors that can achieve high‐speed photoresponse and high responsivity with broadband detection are essential for bio‐health monitoring, imaging, chemical sensing, and many other applications. Herein a high‐performance inorganic–organic hybrid photodetector based on a heterojunction of exfoliated 2D tungsten diselenide (WSe2) layers and solution‐processable poly(3‐hexylthiophene‐2,5‐diyl), P3HT is reported. The heterojunction shows enhanced exciton harvesting through long‐range energy transfer from P3HT to WSe2, which is confirmed using photoluminescence quenching and fluorescence decay measurements. The detector shows broadband light detection from visible to near‐infrared (NIR) (400−1100 nm), and air‐stable device performance. The device exhibits the highest responsivity of 17.6 AW−1 for low incident light intensity (<10−5 W cm−2) at 640 nm wavelength of light. Furthermore, a fast photoresponse speed with a rise/fall time of 9.5/5.1 µs, which retained its performance for more than four months under ambient conditions is demonstrated. The superior device performance presented here using an inorganic–organic hybrid heterojunction is the key to producing novel high‐performance and air‐stable photodetectors with broad spectral bandwidth. [ABSTRACT FROM AUTHOR]

External quantum efficiency (EQE) roll‐off under high current injection has been one of the major limiting factors toward the development of organic semiconductor laser diodes (OSLDs). While significant progress in this regard has been made on organic semiconductors (OSCs) emitting in the blue–green region of the visible spectrum, OSCs with longer wavelength emission (>600 nm) have fallen behind in both material development and the advancement in device architectures suitable for the realization of OSLDs. Therefore, to make simultaneous incremental advancements, a host–guest system comprising of a high performing poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole) (F8BT) polymer and an efficient small molecule laser dye, dithiophenyl diketopyrrolopyrrole (DT‐DPP), is used. This combination provides an extremely low amplified spontaneous emission threshold of 4.2 µJ cm−2 at an emission wavelength of 620 nm. The solution‐processed organic light‐emitting diodes (OLEDs) fabricated using this system exhibit a high external quantum efficiency (EQE) of 2.6% with low efficiency roll‐off and high current injection up to 90 A cm−2 to yield ultrahigh luminance of over 1.5 million cd m−2. [ABSTRACT FROM AUTHOR]

Hyperfluorescent organic light‐emitting diodes (HF‐OLEDs) enable a cascading Förster resonance energy transfer (FRET) from a suitable thermally activated delayed fluorescent (TADF) assistant host to a fluorescent end‐emitter to give efficient OLEDs with relatively narrowed electroluminescence compared to TADF‐OLEDs. Efficient HF‐OLEDs require optimal FRET with minimum triplet diffusion via Dexter‐type energy transfer (DET) from the TADF assistant host to the fluorescent end‐emitter. To hinder DET, steric protection of the end‐emitters has been proposed to disrupt triplet energy transfer. In this work, the first HF‐OLEDs based on structurally well‐defined macromolecules, dendrimers is reported. The dendrimers contain new highly twisted dendrons attached to a Cibalackrot core, resulting in high solubility in organic solvents. HF‐OLEDs based on dendrimer blend films are fabricated to show external quantum efficiencies of >10% at 100 cd m−2. Importantly, dendronization with the bulky dendrons is found to have no negative impact to the FRET efficiency, indicating the excellent potential of the dendritic macromolecular motifs for HF‐OLEDs. To fully prevent the undesired triplet diffusion, Cibalackrot dendrimers HF‐OLEDs are expected to be further improved by adding additional dendrons to the Cibalackrot core and/or increasing dendrimer generations. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) dynamics of Ir(ppy)(sub 3)-cored dendrimers with the simple molecule Ir(ppy)(sub 3) in solution, blends, and neat films are discussed. Extensive aggregation of Ir(ppy)(sub 3) molecules is indicated by their rough surface with aggregated region of rodlike structure, as obtained by atomic force microscopy, which suggests that the PL quenchers in neat Ir(ppy)(sub 3) films may be excimers.

Photophysical studies of pseudo-p-distyryl[2.2]paracyclophane, a model molecule of a stilbene dimer arranged in a brick-wall geometry, in tetrahydrofurane solution indicate the existence of at least two conformers in the ground state. Ground state energy has a shallow minimum with respect to the torsinal angle between the styryl side group and the paracyclophane core around the zero position, with the lowest energy conformation at a torsional angle of -21 degree.

Hyperfluorescent organic light-emitting diodes (OLEDs) have allowed remarkable device performances to be achieved using fluorescent emitters. Superior device performance has been realised using thermally evaporated emissive layers. However, for future large-scale commercialisation, it is essential to obtain similar device performances using low-cost solution-processing techniques. In the case of hyperfluorescent OLEDs, there remains a delicate interplay of molecular interactions and spacing between the three active components: a host, a thermally activated delayed fluorescent (TADF) assistant host, and a fluorescent emitter. Dispersion of the materials is a dominating factor towards the device efficiencies, making efficient solution-processed devices all the more difficult to achieve. Herein, we have demonstrated solution-processed hyperfluorescent devices with an external quantum efficiency (EQE) of 15.3% using cibalackrot as the fluorescent emitter and 4CzIPN-tBu as the TADF assistant host in CBP. By studying the use of either 4CzIPN or 4CzIPN-tBu as the TADF assistant host in both ternary and host-free binary blends, we found that the addition of tert-butyl groups to the TADF material made a significant contribution to the device performance. These sterically hindered groups effectively reduced losses caused by triplet diffusion between the TADF assistant host and the fluorescent emitter by spatially separating adjacent molecules and making a concurrent frontier molecular orbital (FMO) less likely. [ABSTRACT FROM AUTHOR]

The field of organic photodiodes (OPDs) has witnessed continuous development in the last decade. Although a considerable portion of electron‐donating materials are polymers, there has been an existential gap in deciphering the influence of the polymer's molecular‐weight on the photodiode performance. We take up OPDs based on 5,5′‐[(9,9‐Dioctyl‐9H‐fluorene‐2,7‐diyl)bis(2,1,3‐benzothiadiazole‐7,4diylmethylidyne)]bis[3‐ethyl‐2‐thioxo‐4‐thiazolidinone] (FBR) acceptor material blended with three different molecular‐weights of defect‐free form of a well‐known donor polymer poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) are taken up, and their optoelectronic performance along with morphological characteristics are studied. Disparity of up to a decade in key photodetecting characteristics is observed. Further, the tools of near‐edge X‐ray absorption fine‐structure spectroscopy, resonant soft X‐ray scattering spectroscopy, atomic force microscopy, and time‐delayed collection‐field measurements are employed to decipher the difference in the fundamental photo‐physical processes and the operating mechanisms of the OPDs. It is concluded that the molecular weight and the resulting morphology of the active layer strongly influence photodiode performance, in particular, dark current, linear dynamic range, and specific‐detectivity. [ABSTRACT FROM AUTHOR]

Organic semiconductors possessing tightly bound Frenkel excitons are known to be attractive candidates for demonstrating polariton lasing at room temperature. As polariton lasing can occur without inversion, it is a potential route to very low threshold coherent light sources. However, so far, the thresholds of organic polariton lasers have generally been much higher than those of organic photon lasers. Here this problem has been addressed by investigating two new organic molecules with a structure combining fluorene and carbazole groups. The materials are readily deposited from solution and exhibit high photoluminescence quantum yields, high absorption coefficients, and large radiative decay rates in neat films. Room temperature polariton lasing is realized in both materials with incident thresholds of 13.5 and 9.7 µJ cm−2, corresponding to absorbed thresholds of 3.3 and 2.2 µJ cm−2, respectively. These are the lowest values reported to date for polariton lasing in organic semiconductor materials, and approach typical values for organic photon lasers. The step‐like power dependent blue‐shift of polariton modes indicates an interplay between different depletion channels of the exciton reservoir. This work brings practical room temperature polaritonic devices and future realization of electrically driven polariton lasers a step closer. [ABSTRACT FROM AUTHOR]

The ability of a light‐sensor to detect fast variation in incident light intensity is a vital feature required in imaging and data transmission applications. Solution‐processed bulk heterojunction (BHJ) type organic photodiodes (OPDs) have gone through key developments, including dark current mitigation and longer linear dynamic range. In contrast, there has been less focus on increasing OPD response speed (f–3dB). Here, bulk heterojunction OPDs based on electron‐donating polymer poly[thiophene‐2,5‐diyl‐alt‐5,10‐bis((2‐hexyldecyl)oxy)dithieno[3,2‐c:3′,2′‐h][1,5]naphthyridine‐2,7‐diyl] (or PTNT) and electron‐accepting phenyl‐C71‐butyric acid methyl ester (or PC71BM) are reported. The intrinsic charge transport characteristics required for fast speed OPDs are discussed, and an analytical model for the same is developed. The OPDs present 0.8 MHz f–3dB under no applied voltage bias for a typical blend ratio of 1:1 by weight. It is shown that balanced electron and hole mobility is a critical criterion for faster speed OPDs, which can be realized by tuning the composition ratio of the bulk heterojunction. By tuning PTNT and PC71BM blend ratio, the f–3dB was successfully raised by more than quadruple to 4.5 MHz. The findings provide a tool to set device architecture for faster next‐generation light sensors. [ABSTRACT FROM AUTHOR]

N‐Heterocyclic carbene (NHC) cyclometalated gold(III) complexes remain very scarce and therefore their photophysical properties remain currently underexplored. Moreover, gold(III) complexes emitting in the blue region of the electromagnetic spectrum are rare. In this work, a series of four phosphorescent gold(III) complexes was investigated bearing four different NHC monocyclometalated (C^C*)‐type ligands and a dianionic (N^N)‐type ancillary ligand ((N^N)=5,5'‐(propane‐2,2‐diyl)bis(3‐(trifluoromethyl)‐1 H‐pyrazole) (mepzH2)). The complexes exhibit strong phosphorescence when doped in poly(methyl methacrylate) (PMMA) at room temperature, which were systematically tuned from sky‐blue [λPL=456 nm, CIE coordinates: (0.20, 034)] to green [λPL=516 nm, CIE coordinates: (0.31, 0.54)] by varying the monocyclometalated (C^C*) ligand framework. The complexes revealed high quantum efficiencies (ϕPL) of up to 43 % and excited‐state lifetimes (τ0) between 15–266 μs. The radiative rate constant values found for these complexes (kr=103–104 s−1) are the highest found in comparison to previously known best‐performing monocyclometalated gold(III) complexes. Density functional theory (DFT) and time‐dependent DFT (TD‐DFT) calculations of these complexes further lend support to the excited‐state nature of these complexes. The calculations showed a significant contribution of the gold(III) metal center in the lowest unoccupied molecular orbitals (LUMOs) of up to 18 %, which was found to be unique for this class of cyclometalated gold(III) complexes. Additionally, organic light‐emitting diodes (OLEDs) were fabricated by using a solution process to provide the first insight into the electroluminescent (EL) properties of this new class of gold(III) complexes. [ABSTRACT FROM AUTHOR]

Over the years, achieving efficient electroluminescence (EL) while simultaneously having low light amplification thresholds under optical excitation has been the key to progression toward the long‐thought objective of electrically pumped organic lasers. While significant progress in this regard has been made for organic semiconductors emitting in the blue–green region of the visible spectrum, organic laser dyes with low‐energy emission (>600 nm) still suffer from high amplified spontaneous emission (ASE) thresholds and low external quantum efficiencies (EQEs) in devices. Herein, low ASE thresholds and efficient EL are reported from a solution‐processable organic laser dye dithiophenyl diketopyrrolopyrrole (DT‐DPP). The ASE threshold of 4 µJ cm−2 at the wavelength of 620 nm is obtained while making constructive use of triplet excitons by doping DT‐DPP in a green‐emitting host matrix, which exhibits thermally activated delayed fluorescence (TADF). The organic light‐emitting diode fabricated from this system gives a high EQE of 7.9% due to the efficient utilization of triplet excitons. Transient EL studies further show that a high reverse intersystem crossing rate is crucial in achieving lasing under electrical pumping from such TADF‐assisted fluorescent systems. [ABSTRACT FROM AUTHOR]

High mechanical flexibility and wavelength tunability of organic semiconductor materials have propelled the development of organic semiconductor lasers (OSLs) as a complementary technology to current inorganic lasers. While excellent progress has been made across multiple aspects of OSLs, demonstration of long‐pulse operation [quasi‐continuous wave (qCW) or continuous wave (CW)] lasing has presented significant challenges due to the detrimental accumulation of triplets under long‐pulse photoexcitation and substantial quenching of singlet excitons, arising from singlet‐triplet annihilation (STA). In particular, qCW or CW lasing from solution‐processed OSL materials has not been reported, and thus remains a long‐thought objective in optoelectronic research. Using a novel bis(N‐carbazolylstyryl)‐9,9‐dihexylfluorene (BSFCz), the first solution‐processable organic laser dye demonstrating lasing oscillation in the long‐pulse photoexcitation regime (up to 10 ms pulse width) with a low threshold (420 W cm−2), which in part can be attributed to its negligible spectral overlap between triplet excited‐state absorption and laser emission, is herein reported. Temporal emission profiles below and above the lasing threshold also demonstrate that STA has a negligible effect on emission. These combined observations show BSFCz incur low losses due to triplet excited‐states, leading to extremely small changes in lasing thresholds when moving from pulsed to qCW (>1 ms) excitation. [ABSTRACT FROM AUTHOR]

Organic semiconductor dyes have attracted high interest as laser gain media owing to their judicious features of solution processability, lightweight, high mechanical flexibility, high wavelength‐tunability, and low‐cost manufacture. In this work, fluorene‐carbazolylstyryl hybrids are reported, SFCz and BSTFCz, as new solution processable organic semiconductor laser dyes to show high molar extinction coefficients (up to 1.98 × 105 dm3 mol−1 cm−1), high photoluminescence quantum yields (up to 81 ± 4%), high radiative decay constants (up to 1.24 × 109 s−1), and low film amplified spontaneous emission thresholds (down to 0.70 µJ cm−2). By using mixed‐order distributed feedback laser structures, extremely low lasing threshold of 0.5 µJ cm−2 is achieved. To elucidate their electroluminescent properties, simple solution‐processed organic light‐emitting diodes based on the new materials are fabricated to show good external quantum efficiencies (2%) and high brightness (≈2800 cd m−2). The results indicate the ease in material synthesis and fabrication enabling solution‐processed low‐threshold lasing toward future injection laser. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) emitters can exhibit high quantum efficiencies by harvesting triplet excitons through efficient reverse intersystem crossing. Reports on efficient TADF based light‐emitting field‐effect transistors (LEFETs) are rare. Moreover, despite efficient TADF organic light‐emitting diodes (OLEDs), most devices have thermally evaporated multilayer device designs. In this work, highly efficient solution processed LEFETs using ACRXTN [3‐(9,9‐dimethylacridin‐10(9H)‐yl)‐9H‐xanthen‐9‐one] are demonstrated to show high external quantum efficiencies (EQEs) of ≈1% and on/off ratios (≈105) at low operating voltages (≈22 V) with negligible EQE roll‐off even at ≈1,500 cd m–2. The same emitter is further studied in solution‐processedOLEDs with a simple architecture to achieve high peak EQEs (≈16%) and brightness (>1000 cd m–2). The OLEDs retain a high EQE (≈10%) at 20 000 cd m–2, indicating excellent charge balance even with such simple device architecture. Our optical simulations identify EQE discrepancy in the two devices, mainly arisen from a poorer light out‐coupling efficiency in the LEFETs (0.8%) than that (≈24%) in the OLEDs. This work shows state‐of‐the‐art of solution‐processed TADF LEFETs and OLEDs with simple device architectures and negligible EQE roll‐off. [ABSTRACT FROM AUTHOR]

Strong coupling between an exciton and a cavity photon mode offers the promise of lower lasing thresholds, which has attracted interest in organic systems working toward electrically injected lasing. However, current organic polariton lasers have yet to exhibit thresholds beyond the reach of traditional lasers. Here, we investigate the possibility of energy funnelling from host to guest in a polariton system. We construct a material blend containing a dithiophenyl diketopyrrolopyrrole dye with an electrically conductive fluorene–benzothiadiazole co-polymer matrix. We demonstrate that a polariton system can exhibit efficient host to guest energy transfer while maintaining both strong exciton–polariton coupling and polariton emission. We expect that energy funnelling will become an important tool to drive down polariton laser thresholds in organic systems. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated that in thermally activated delayed fluorescence (TADF) materials, efficient reverse intersystem crossing occurs from nonradiative triplet exited states to radiative singlet excited states due to a small singlet–triplet energy gap. This reverse intersystem crossing significantly influences exciton annihilation processes and external quantum efficiency roll‐off in TADF based organic light‐emitting diodes (OLEDs). In this work, a comprehensive exciton quenching model is developed for a TADF system to determine singlet–singlet, singlet–triplet, and triplet–triplet annihilation rate constants. A well‐known TADF molecule, 3‐(9,9‐dimethylacridin‐10(9H)‐yl)‐9H‐xanthen‐9‐one (ACRXTN), is studied under intensity‐dependent optical and electrical pulse excitation. The model shows singlet–singlet annihilation dominates under optically excited decays, whereas singlet–triplet annihilation and triplet–triplet annihilation have strong contribution in electroluminescence decays under electrical pulse excitation. Furthermore, the efficiency roll‐off characteristics of ACRXTN OLEDs at steady state is investigated through simulation. Finally, singlet and triplet diffusion length are calculated from annihilation rate constants. [ABSTRACT FROM AUTHOR]

The rapid development of charge transporting and light‐emitting organic materials in the last decades has advanced device performance, highlighting the high potential of light‐emitting transistors (LETs). Demonstrated for the first time over 15 years ago, LETs have transformed from an optoelectronic curiosity to a serious competitor in the race for cheaper and more efficient displays, also showing promise for injection lasers. Thus, what is an LET, how does it work, and what are the current challenges for its integration into mainstream technologies? Herein, some light is shed on these questions. This work also provides the fundamental working principle of LETs, materials that have been used, and device physics and architectures involved in the progression of LET technology. The state‐of‐the‐art development of LETs is also explored as prospect avenues for the future of research and applications in this area. [ABSTRACT FROM AUTHOR]

The procedure and the impacts of the electrochemical doping in various electrolyte-gated polymer transistors are discussed. The analysis proves that low gate voltages lead to high channel currents in these substances.