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We report the development of light-emitting dendrimers with heteroleptic or homoleptic iridium(III) complexes at the core, with one, two, or three first- or second-generation biphenyl-based dendrons attached to the 2-phenylpyridyl ligand that is involved in the emission of light. The 5-phenyl-1-methyl3-n-propyl-1H-1,2,4-triazole co-ligand was not dendronised and was not involved in the emission process. The dendrimers with two emissive ligands were found to have the highest solution photoluminescence quantum yields (PLQYs) which were greater than 90% independent of the dendrimer generation. The second-generation dendrimers were all found to have higher neat film PLQYs than their first-generation counterparts due to the increased shielding of the emissive core by the dendrons and surface groups. The maximum external quantum efficiencies of devices made from the neat film and a guest:host blend of the second-generation dendrimer with two emissive ligands were found to be the highest (7.5% and 15.8%, respectively), which was attributed to a balance between the interactions required for charge transport and minimising those that lead to non-radiative processes. Thus, we have demonstrated that combining dendrimer generation and number of emissive dendronised ligands is a viable strategy for optimising light-emitting dendrimer OLED performance. [ABSTRACT FROM AUTHOR]

Tris‐bidentate iridium(III) complexes used in organic light‐emitting diodes (OLEDs) are typically homoleptic or heteroleptic with three or two identical emissive ligands, respectively. Herein red phosphorescence emitting dendrimers composed of first generation biphenyl dendrons, 2‐ethylhexyloxy surface groups and an iridium(III) complex core with three, two or one emissive [4‐phenyl]−2‐[thiophen‐2‐yl]quinoline ligands are reported. The dendrimers have similar photoluminescence quantum yields (PLQYs) in solution (84–88%), neat film (23–25%) and when blended with tris(4‐carbazoyl‐9‐ylphenyl)amine (72–73%), enabling the effect of the number of emissive ligands on OLED performance to be determined. The external quantum efficiency (EQE) of OLEDs composed of neat dendrimer films increased with decreasing number of emissive ligands, with the device composed of the dendrimer having a single emissive ligand having an EQE of 9.2%, which is almost double that expected from a bottom emitting device and a film PLQY of 25 ± 3.6%. The emission is Lambertian and the higher‐than‐expected EQE is ascribed to alignment of the single emissive ligand being optimal for light‐outcoupling. The EQE of OLEDs containing the blend film also increased with decreasing emissive number of ligands (maximum EQE = 15.4%). [ABSTRACT FROM AUTHOR]

Film‐based fluorescence sensors are attractive for rapid and on‐site detection of illicit drugs, due to their potential for portability, high sensitivity and reusability. Three new bay‐substituted perylene diimide derivatives are synthesized , P1‐CH3 (1‐methyl), P1‐CF3 (1‐trifluoromethyl), and P1‐(CF3)2 (1,7‐di‐trifluoromethyl) that can be solution processed into thin films capable of detecting methamphetamine hydrochloride (MA•HCl) and cocaine•HCl via a luminescence quenching mechanism. The ionization potentials of the materials are sufficiently high to enable photoinduced hole transfer to occur, which led to the luminescence quenching. The trifluoromethyl‐substituted PDIs exhibit superior sensitivity and reversibility of the luminescence quenching process. In particular, P1‐(CF3)2 shows a limit of detection to MA•HCl of ≈100 ng after a 15‐second exposure, and its luminescence can be fully recovered either through mild heating or being placed in an air flow. Furthermore, by using the luminescence quenching and recovery responses of four PDI sensing materials it is possible to differentiate MA•HCl, cocaine•HCl, from aspirin, caffeine, sugar, and (sebum) skin oil in around a minute. [ABSTRACT FROM AUTHOR]

Controlled functionalization of 2D black phosphorus (BP) nanosheets provides unique opportunities to tune their chemical, physical, and electronic properties. Herein, the preparation of single‐atom nickel‐doped BP (Ni–BP) sheets using a simple solution‐based strategy is reported. Using the Ni–BP sheets as a passivation layer on top of a perovskite film leads to standard perovskite solar cells (PSCs) with improved performance. The standard n–i–p PSCs with the Ni–BP interlayer achieve maximum power conversion efficiencies of over 22%, with negligible hysteresis and a modest improvement in stability when subjected to different testing conditions. The perovskite films prepared with Ni–BP sheets‐based passivation are found to have reduced defect densities as well as improved charge‐transfer properties and carrier lifetimes. Density‐functional theory calculations support the experimental results through showing that the atomic Ni‐doping increases the work function of the BP interlayer, enabling better hole extraction, as well as increasing the surface hydrophobicity of the BP layer, hence reducing water sorption into the perovskite film. [ABSTRACT FROM AUTHOR]

Singlet fission (SF) is a potential avenue for augmenting the performance of silicon photovoltaics, but the scarcity of SF materials energy‐matched to silicon represents a barrier to the commercial realization of this technology. In this work, a molecular engineering approach is described to increase the energy of the S1 and T1 energy levels of diketopyrrolopyrrole derivatives such that the energy‐level requirements for exothermic SF and energy‐transfer to silicon are met. Time‐resolved photoluminescence studies show that the silicon‐matched materials are SF active in the solid state, forming a correlated triplet pair 1(TT) – a crucial intermediate in the SF process – as observed through Herzberg‐Teller emission from 1(TT) at both 77 K and room temperature. Transient electron paramagnetic resonance studies show that the correlated triplet pair does not readily separate into the unbound triplets, which is a requirement for energy harvesting by silicon. The fact that the triplet pair do not separate into free triplets is attributed to the intermolecular crystal packing within the thin films. Nevertheless, these results demonstrate a promising route for energy‐tuning silicon‐matched SF materials. [ABSTRACT FROM AUTHOR]

In‐field rapid and reliable identification of nerve agents is critical for the protection of Defence and National Security personnel as well as communities. Fluorescence‐based detectors can be portable and provide rapid detection of chemical threats. However, most current approaches cannot differentiate between dilute vapors of nerve agent classes and are susceptible to false positives due to the presence of common acids. Here a fluorescence‐based method is shown for rapid differentiation between the V‐series and phosphonofluoridate G‐series nerve agents and avoids false positives due to common acids. Differentiation is achieved through harnessing two different mechanisms. Detection of the V‐series is achieved using photoinduced hole transfer whereby the fluorescence of the sensing material is quenched in the presence of the V‐series agent. The G‐series is detected using a turn‐on mechanism in which a silylated excited state intramolecular proton transfer sensing molecule is selectively deprotected by hydrogen fluoride, which is typically found as a contaminant and/or breakdown product in G‐series agents such as sarin. The strategy provided discrimination between classes, as the sensor for the G‐series agent class is insensitive to the V‐series agent, and vice versa, and neither responded to common acids. [ABSTRACT FROM AUTHOR]

Thin films of two poly(dendrimer)s were studied for the detection of trace quantities of nitro-based taggants and explosives. The poly(dendrimer) structures consist of side chain-conjugated triphenylamine-based dendritic chromophores attached to a non-conjugated polymer backbone. The poly(dendrimer)s differ in terms of the conjugation length, steric bulk and surface groups of the chromophores and we investigated the effects of these differences on sensing performance. We found that the addition of first-generation biphenyl-based dendrons to the chromophores of one of the polymers, P2 , resulted in greater photoluminescence quenching, sensitivity and recovery to pulses of the vapours of the nitroaliphatic taggant 2,3-dimethyl-2,3-dinitrobutane (DMNB) and the nitroaromatic analyte 2,4-dinitrotoluene (2,4-DNT) compared with the other polymer, P1. We employed neutron reflectometry to characterise the vapour uptake of both poly(dendrimer)s and a structurally similar triphenylamine-based dendrimer D1 for comparison. The results show that the P2 has a mass density of 0.91 ± 0.01 v. 1.01 ± 0.01 g cm−3 for both P1 and D1 and can absorb at least twice the amount of 2,4-DNT. These results show how increasing the dendritic character of the poly(dendrimer) architecture provides a route for optimising vapour uptake and improving sensing performance in the solid state. Thin films of two poly(dendrimer)s differing in conjugation length, steric bulk and surface groups were studied for the detection of trace quantities of nitro-based taggant and explosive vapours. Addition of first-generation biphenyl-based dendrons led to a decrease in mass density, an increase in analyte sorption and improved detection. (Image credit: Paul L. Burn.) CH23131_TOC.jpg [ABSTRACT FROM AUTHOR]

Bulk heterojunction organic solar cells have undergone significant improvements in power conversion efficiency and stability over the past decade. However, translation from laboratory-scale devices to commercial panels is complicated by the sensitivity of the efficiency to morphological changes, which requires delicate control of the processing conditions. A homojunction architecture, with only a single chromophoric material in the light absorbing layer, could provide a pathway to overcoming problems associated with controlling complex blend morphologies. However, to achieve that goal the organic semiconductor would need to have a dielectric constant of ≈10 such that free charge carriers are formed directly upon photoexcitation. In this study we explore the effect of fluorination on the low and high frequency dielectric constants of two sets of materials with monomeric (A′–A–D) or dimeric (A′–A–D–D–A–A′) structures, where A′ is an aldehyde, A is a protonated or fluorinated benzothiadiazole, and D is a glycolated 4H-cyclopenta[2,1-b:3,4-b′]dithiophene (CPDT) donor unit. Fluorination was found to have only a small effect on the film absorption properties (small blue shift and decreased coefficient), but led to films with increased density relative to the protonated material (1.44 g cm−3versus 1.32 g cm−3), and dispersive unbalanced electron (≈10−6 cm2 V−1 s−1) and hole transport (≈10−5 cm2 V−1 s−1). Critically, while the low frequency dielectric constant of the fluorinated dimeric material was larger than that of the protonated (8.3 versus 7.3), the optical frequency dielectric constant that is thought to be critical for exciton dissociation was smaller (3.3 versus 3.6). [ABSTRACT FROM AUTHOR]

The strategy of using a bulk-heterojunction light-absorbing layer has led to the most efficient organic solar cells. However, optimising the blend morphology to maximise light absorption, charge generation and extraction can be challenging. Homojunction devices containing a single component have the potential to overcome the challenges associated with bulk heterojunction films. A strategy towards this goal is to increase the dielectric constant of the organic semiconductor to ≈10, which in principle would lead to free charge carrier generation upon photoexcitation. However, the factors that affect the thin film dielectric constants are still not well understood. In this work we report an organic semiconductor material that can be solution processed or vacuum evaporated to form good quality thin films to explore the effect of chromophore structure and film morphology on the dielectric constant and other optoelectronic properties. 2,2′-[(4,4,4′,4′-Tetrakis{2-[2-methoxyethoxy]ethyl}-4H,4′H-{2,2′-bi[cyclo-penta[2,1-b:3,4-b′]dithiophene]}-6,6′-diyl)bis(methaneylylidene)]dimalononitrile [D(CPDT-DCV)] was designed to have high electron-affinity end groups and low ionisation-potential central moieties. It can be processed from solution or be thermally evaporated, with the film morphology changing from face-on to a herringbone arrangement upon solvent or thermal annealing. The glycol solubilising groups led to the static dielectric constant (taken from capacitance measurements) of the films to be between 6 and 7 (independent of processing conditions), while the optical frequency dielectric constant depended on the processing conditions. The less ordered solution processed film was found to have the lowest optical frequency dielectric constant of 3.6 at 2.0 × 1014 Hz, which did not change upon annealing. In contrast, the more ordered evaporated film had an optical frequency dielectric constant 20% higher at 4.2 and thermal annealing further increased it to 4.5, which is amongst the highest reported for an organic semiconductor at that frequency. Finally, the more ordered evaporated films had more balanced charge transport, which did not change upon annealing. [ABSTRACT FROM AUTHOR]

Materials engineering is key to improving the stability and photovoltaic parameters of inverted perovskite solar cells (PSCs). This work presents the effect of two different fluorinated additives on the performance of PSCs containing the archetypal three‐dimensional perovskite, methylammonium lead triiodide (MAPbI3). 3‐(2,3,4,5,6‐Pentafluorophenyl)propylammonium iodide (FPAI) is added to the anode modifying layer and (2,3,4,5,6‐pentafluorophenyl)methylammonium bromide (FMABr) is blended into the perovskite layer. The inverted devices containing FPAI in the anode modifying layer and 0.32 mol% of FMABr from the perovskite precursor solution had hysteresis‐free current density‐voltage characteristics and a maximum power conversion efficiency of 22.3%, which is an absolute increase of 1.7% compared to the MAPbI3 device (20.6%) of the same architecture but without the additives. [ABSTRACT FROM AUTHOR]

Two light-emitting dendrimers composed of red phosphorescent fac-tris[2-(thiophen-2-yl)-4-(phenyl)quinoline]iridium(III) cores and either blue (BR) or green (GR) thermally activated delayed fluorescence-based (TADF-based) dendrons have been prepared. The dendrimer emission in solution was found to be primarily from the phosphorescent core independent of the dielectric constant of the solvent used. Irrespective of the medium, time-resolved emission spectroscopy (TRES) at room temperature and 77 K provided evidence for the dendrons acting as energy pools for emission from the core. The maximum solution photoluminescence quantum yields (PLQYs) of both dendrimers was around 60%, which was similar to the model core, fac-tris[2-(thiophen-2-yl)-4-(p-tolyl)quinoline]iridium(III) (TQIr). The neat film PLQY values were lower, being 19% and 8% for BR and GR, respectively. However, when blended with tris(4-carbazoyl-9-ylphenyl)amine (TCTA) at low concentration the film PLQY values increased to the value measured for TQIr in solution (≈60%) indicating that the smaller neat film PLQY values was due to intermolecular interchromophore interactions. The external quantum efficiencies (EQEs) for bilayer OLEDs containing the neat emissive layers of BR and GR were 2.6% and 0.9%, respectively, which was consistent with the low PLQY values of the neat films. Finally, the solution processed OLEDs fabricated using 0.1 mol% of BR and GR blended with TCTA resulted in red emission with maximum EQEs of 13.5% and 11.0%, respectively. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescent (TADF) materials are extensively investigated as organic light‐emitting diodes (OLEDs) with TADF emitting layers demonstrating high efficiency without the use of heavy metal complexes. Therefore, solution‐processable and printable TADF emitters are highly desirable, moving away from expensive vacuum deposition techniques. In addition, using emissive materials not requiring an external host simplifies the fabrication process significantly. Herein, OLEDs using a solution‐processable TADF polymer that do not need an external host are introduced. The non‐conjugated TADF polymer features a TADF emitter (4‐(9H‐carbazol‐9‐yl)‐2‐(3′‐hydroxy‐[1,1′‐biphenyl]‐3‐yl)‐isoindoline‐1,3‐dione) as a side chain, as well as a hole‐transporting side chain and an electron‐transporting side chain on an inactive polymer backbone. All organic layers of the OLEDs are fabricated using solution processing methods. The OLEDs with inkjet‐printed emissive layers have comparable maximum current and external quantum efficiency as their spin‐coated counterparts, exceeding luminance of 2000 cd m−2. The herein‐explored strategy is a viable route toward self‐hosted printable TADF OLEDs. [ABSTRACT FROM AUTHOR]

Dual emission light‐emitting dendrimers composed of phosphorescent fac‐tris[2‐phenylpyridyl]iridium(III) [Ir(ppy)3] cores and thermally activated delayed fluorescence‐based (TADF‐based) dendrons have been prepared. The TADF‐based dendrons are designed to have green or blue emission. The dendrimers show solvatochromism, with the emission switching between phosphorescence and TADF depending on the medium in which the measurement is undertaken. Time‐dependent photoluminescence (PL) spectra measurements show that the TADF dendrons can act as an energy pool for emission from the phosphorescent core. The PL quantum yields (PLQYs) are found to be strongly dependent on the dielectric constant of the solvent, ranging from as high as 76% to as low as 0.3%. Neat films of the dendrimers are found to have relatively balanced hole and electron mobilities of order 10–6 cm2 V–1 s–1, with bilayer organic light‐emitting diodes (OLEDs) containing neat emissive layers having a maximum external quantum efficiency (EQE) of 4.7% for a film having a PLQY of 12%. Finally, the solution processed OLEDs fabricated using 0.4 mol% of the dendrimers blended with 9‐[3‐(9H‐carbazol‐9‐yl)phenyl]‐9H‐carbazole‐3‐carbonitrile result in green emission with maximum EQEs of 9.8% and 15.1% for the dendrimers with green and blue emissive TADF dendrons, respectively. [ABSTRACT FROM AUTHOR]

We report thermally activated delayed fluorescence (TADF) poly(dendrimer)s, composed of a norbornenyl-derived polymer backbone and dendritic side-chain chromophores comprising benzonitrile as the electron acceptor and two differently substituted first-generation 3,6-disubstituted carbazoles as electron donors. In particular, we compare the effect of the donor strength on the properties of the poly(dendrimer)s and their dendrimer analogues. The groups attached to the carbazolyl moieties to form the donor units were either 9,9-di-n-propylfluorene or diphenylamine. All four compounds were found to have TADF emission with neat film photoluminescence quantum yields (PLQYs) of up to 27%. The di-n-propylfluorenyl groups were found to afford a higher degree of protection from intrapolymer interchromophore interactions along the poly(dendrimer) backbone, and the solution and neat film PLQYs were similar. Photoluminescence studies performed at 77 K revealed that the triplet excitons can migrate along the poly(dendrimer) chain until they reach a chromophore that has the configuration required for charge transfer emission. Also, neat films of the poly(dendrimer)s were found to transport holes and electrons with reasonably balanced mobilities, whilst the dendrimers only had measurable hole mobilities. Organic light-emitting diodes with neat and blended emissive layers were found to have modest performance. [ABSTRACT FROM AUTHOR]

Red‐emitting organic light‐emitting diodes (OLEDs) are important for displays and lighting, with the latter benefiting from solution processable materials, which would enable low embedded energy, scalable fabrication. Herein, the effect of annealing and phase separation on the performance of solution‐processed OLEDs incorporating a light‐emitting layer composed of the exciplex host, m‐MTDATA:OXD‐7, and a red phosphorescent light‐emitting dendrimer, Ir(tDCpq)3, is described. Solution‐processed OLEDs containing an annealed emissive layer with a low dendrimer concentration (2 wt%) are found to have the best performance, which is higher than the device in which the light‐emitting layer is not annealed. The improvement in the performance of the annealed device is ascribed to improved charge mobility within the emissive layer caused by phase separation of the OXD‐7. The OLEDs containing annealed m‐MTDATA:OXD‐7:(2 wt%) Ir(tDCpq)3 have maximum current, power, and external quantum efficiencies of 17.9 cd A−1, 19.4 lm W−1, and 14.8 ± 0.6%, respectively. The fact that the maximum external quantum efficiency (EQE) of 14.8% is larger than that expected based on the photoluminescence quantum yield (PLQY) and the normal out‐coupling efficiency of 20% from a bottom‐emitting device is determined to arise from the different pathways of exciton formation under photoexcitation and charge injection. [ABSTRACT FROM AUTHOR]

Bulk heterojunction organic solar cells continue to show steady photoconversion efficiency improvements. However, single component organic solar cells are a particularly attractive alternative due to the relative simplicity of device manufacture. It has been proposed that organic semiconductors with a high dielectric constant (≈10) could give rise to spontaneous free charge carrier generation upon photoexcitation. In this manuscript, factors are explored that affect the dielectric constant of organic semiconductors, particularly the optical‐frequency dielectric constant. The properties of monomers, dimers and trimers of two isoelectronic families of materials that have acceptor units composed of one or two dicyanovinylbenzothiadiazole moieties and one to three donor units are compared. The donor components are composed of either fluorenyl or cyclopentadithiophene moieties with the same glycol‐based solubilizing groups. It is found that chromophore planarity and orientation with respect to the substrate, and film density affect the optical and electronic properties of the materials, especially the high‐frequency dielectric constant. The results also indicate that delocalization of the highest occupied and lowest unoccupied molecular orbitals is a critical factor. The dimer with two dicyanovinylbenzothiadiazole moieties and two dithienocyclopentadiene units is found to have the highest optical frequency dielectric constant and overall performance. [ABSTRACT FROM AUTHOR]

The photophysical and charge transport properties of neat and blend films of fac-tris[2-phenylpyridinato-C2,N]iridium(III) [Ir(ppy)3]-cored light-emitting dendrimers and tris(4-carbazoyl-9-ylphenyl)amine (TCTA)-based hosts, with each combination having the same first generation dendrons were measured and compared. The first generation dendrons were composed of bis(fluorenyl)carbazolyl with n-propyl surface groups, or biphenyl with 2-ethylhexyloxy or t-butyl surface groups. Dendronisation of the emitter and host was found to decrease the energy transfer efficiency from the host to the guest relative to an evaporated Ir(ppy)3:TCTA blend film, with the blend composed of materials with biphenyl dendrons and t-butyl surface groups having the largest decrease. The hole mobilities of the solution processed neat and blend layers were found to be 1–2 orders of magnitude lower than those of the equivalent evaporated films. The blend film containing the host and dendrimer with first generation biphenyl dendrons and 2-ethylhexyloxy surface groups had the highest photoluminescence quantum yield (PLQY), comparable to evaporated Ir(ppy)3:TCTA-based films but the lowest hole mobility (≈10−8 cm2 V−1 s−1). In contrast, the blend with the dendrimers composed of the bis(fluorenyl)carbazolyl dendrons with n-propyl surface groups had a low PLQY but higher hole mobility. It was found for the combinations of these solution processable materials that the hole mobility of the blend film was the limiting factor in OLED performance. Devices containing an emissive layer of the materials with the bis(fluorenyl)carbazolyl dendrons with n-propyl surface groups (11 mole percent of the emitter) had a PLQY of 40.8% but the highest external quantum efficiency of 10.0 ± 0.4%, reaching a maximum luminance of almost 10 000 cd m−2. [ABSTRACT FROM AUTHOR]

Tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA) is a commonly used host material for organic light‐emitting diodes (OLEDs). TCTA has poor solubility and hence to improve solubility the authors have synthesized first‐ and second‐generation TCTA‐based dendrimers with n‐propyl surface groups. These dendrimeric TCTA hosts have improved solubility and similar photophysical properties to TCTA. The hole mobility of solution‐processed TCTA is found to be an order of magnitude less than films formed by evaporation and similar to that of the two dendronized TCTAs (mobilities in the order of 10−5 cm2 V−1 s−1). The hole mobility in the films is found to decrease when a green emissive first‐generation light‐emitting dendrimer is blended with the host materials due to charge trapping on the emissive guest. In the case of the second‐generation host, there is evidence of a degree of phase separation in the film. Organic light‐emitting diodes are fabricated at guest concentrations corresponding to the maximum observed photoluminescence quantum yield (PLQY) and lowest hole mobility. It is found that the external quantum efficiency (EQE) does not always scale with the PLQY, leading to devices that have EQEs higher than expected based on the PLQY and outcoupling of light from a bottom emitting device. [ABSTRACT FROM AUTHOR]

Pre-concentrators are used to improve the detection of analytes that are at low concentration, particularly in air. Polymeric materials are the basis for most pre-concentrators and a strategy to enhance the pre-concentration capability is to add moieties that enhance the polymer matrix–analyte interaction. In this study, the sorption capability of poly(dimethylsiloxane) (PDMS)-based pre-concentrator films towards nitro-based explosives was improved by incorporating a 1,4-divinylbenzene (DVB) derived component. It was found that the mode of DVB incorporation strongly influenced the structure and pre-concentration properties of the resulting film. Films formed from blends of PDMS and DVB (PDMS:DVB) were found to have similar sorption properties as PDMS. The copolymerised (PDMS-co-DVB) film was found to be comprised of voids and spheroidal features, which were retained even after thermal treatment. The copolymer film offered the greatest sorption and retention of analyte vapor, which we attribute to increased material surface area and π–π interactions between the DVB-derived units and the nitroaromatic analytes. The copolymerised film was able to increase the effective concentration of TNT vapor by 3 orders of magnitude relative to the headspace vapor concentration. [ABSTRACT FROM AUTHOR]

Food wastage due to spoiling is a global economic issue and contributes to over-farming and overfishing with real environmental consequences. Smart food packaging is a promising solution to this problem, the concept of which is to incorporate responsive sensors that allow direct monitoring of the gasses released from the decay of food into a label that provides a visual indicator to the consumer as to whether the food is fresh or has spoiled. Here we report two dicyanovinyl-fluorene-benzothiadiazole-based fluorescent compounds, K12 and K12b, both of which showed rapid response to biogenic amines via two independent mechanisms. When primary alkyl amines were present in solution, they underwent an aza-Michael addition with the dicyanovinyl group of the sensing material, resulting in a rapid colour change. The reaction products of K12 and K12b with primary amines showed a decrease and increase in the fluorescence quantum yield, respectively, enabling a unique dual-sensor array with turn-off/turn-on response. In addition, fluorescence quenching via photoinduced hole transfer was observed in the solid-state sensor films with a wide range of primary, secondary and tertiary amines, enabling rapid and sensitive detection of amine vapours. Finally, we show as proof-of-concept that the fluorescence quenching response of sensing films was observable at cadaverine concentrations relevant to the food industry. [ABSTRACT FROM AUTHOR]

Amongst emissive materials for organic light emitting diodes (OLEDs), thermally activated delayed fluorescence (TADF) materials have shown substantial promise in the last few years. For OLEDs, solution processable and printable emissive materials are highly desirable as printing allows for precise patterning without masks, enables deposition of nanometer scale thicknesses and results in minimal wastage of material. Herein, we introduce a solution processable TADF emitting polymer as an emissive material for OLEDs. The bespoke polymer structure features the TADF emitter 4-(9H-carbazol9-yl)-2-(3′-hydroxy-[1,1′-biphenyl]-3-yl)isoindoline-1,3-dione as a pendant group on a poly(methyl methacrylate) based polymer chain. The resulting OLEDs have a peak emission wavelength of 520 nm with a maximum luminance of around 4700 cd m−2. The peak emission wavelength can be blue-shifted by exciplex management to achieve a peak wavelength of 494 nm. Critically, we employed the TADF-containing polymer system to ink-jet print OLEDs, demonstrating that such polymers are viable for printable OLEDs. [ABSTRACT FROM AUTHOR]