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The unique four-level photocycle characteristics of excited-state intramolecular proton transfer (ESIPT) materials enable population inversion and large spectral separation between absorption and emission through their respective enol and keto forms. This leads to minimal or no self-absorption losses, a favorable feature in acting as an optical gain medium. While conventional ESIPT materials with an enol-keto tautomerism process are widely known, zwitterionic ESIPT materials, particularly those with high photoluminescence, are scarce. Facilitated by the synthesis and characterization of a new family of 2-hydroxyphenyl benzothiazole (HBT) with fluorene substituents

Structural direction of hydrogen-bonded thienylenevinylenes reveals that self-assembled to 1D structures exhibit enhanced photoconductivity and charge carrier mobility when compared to 2D sheets.

Diels-Alder photocycloaddition, a well-known textbook reaction, has not been explored in materials chemistry. Herein we describe how this classical photochemistry can be used to modulate the lower critical solution temperature (LCST) of a molecular π-system, which can further be exploited for the controlled transmission of solar radiation for the management of indoor heat and light. An amphiphilic anthracene derivative 9-PA-1 exhibited LCST behavior at 27-32 °C with a reversible transition from a transparent to an opaque phase in water (1-5 mM). Irradiation of a toluene solution of 9-PA-1 with 365 nm light resulted in a [4+2] photocycloadduct 9-PA-2, which exhibited a modulated LCST behavior at 25-27 °C, at a concentration as low as 6 μM. The photocycloaddition of 9-PA-1 was significantly retarded in water, making it a stable candidate for the design of sustainable smart windows. We also demonstrated 100 cm

Volumetric capacitance is a more critical performance parameter for rechargeable power supply in lightweight and microelectronic devices as compared to gravimetric capacitance in larger devices. To this end, we report three electrochromic metallopolymer-based electrode materials containing Fe

High charge carrier mobility is a prerequisite for organic electronics for which molecular arrangement and morphology play a vital role. Herein, we report how the self-assembly of thienylenevinylenes T1 and T2 can achieve morphologically distinct nanostructures with improved charge carrier mobility. Morphological analysis revealed that T1 forms 2D nanosheets that further extend to an array of hierarchical pseudo-1D assemblies, whereas T2 results in 1D nanofibers. Flash photolysis - time resolved microwave conductivity and transient absorption spectroscopy (FP-TRMC and TAS) revealed that 1D fibers of T2 show 1.75 fold higher charge carrier mobility (9.2 × 10

Exciton interactions are not only observed in assembled molecules but also in compounds with multiple chromophores referred to as superchromophores. We have developed isomeric bis-squaraine dyes as superchromophores in which two squaraine chromophores are fused onto the isomeric benzodipyrrole skeleton so as to regulate conformations and to reduce distances between two chromophores. The dyes with benzo[1,2-b:3,4-b']dipyrrole and benzo[1,2-b:5,4-b']dipyrrole moieties exhibited split electronic absorption originated from the intramolecular exciton interaction. The intensity of the split absorption bands varies in correlation with the orientation of chromophores. The isomeric dye with benzo[1,2-b:4,5-b']dipyrrole moiety exhibited a near-infrared absorption associated with the resonance throughout two chromophores. Their electrochemical and spectroelectrochemical properties are distinct from those of monomeric dyes owing to electronic interactions between the two chromophores. Thus, the structural isomerism of the central skeleton significantly affects their optical properties as well as their electrochemical properties.

Efficient optical outcoupling from organic light emitting diodes (OLEDs) is an important challenge in solid state lighting technology. In this work, the effect of an external light extraction layer, prepared using polydimethylsiloxane (PDMS) and zinc oxide (ZnO) nanoparticles, was studied on the performance of red, green, blue and white OLEDs. The self-standing flexible film can effectively address the loss modes at the substrate-air interface. With the application of the layer, a maximum enhancement of about 80% in light outcoupling was observed in white OLEDs. Monochrome OLEDs also showed appreciable enhancement in emission with green having the highest improvement (102%), followed by red (56%) and blue (35%). Finite-difference time-domain (FDTD) simulations were performed for elucidating the mechanism behind the improvement in light extraction due to nanoparticle scattering layer. Total-Field Scattered-Field (TFSF) source was used to simulate the scattering cross-section for different wavelengths. Reduced Fresnel reflections at the air-glass interface and advantageous Mie scattering by ZnO nanoparticles seem to increase the optical outcoupling. This film could be a potential candidate for light extraction in OLEDs because of its facile fabrication, economical precursors, and adaptability to flexible substrates and absence of any possible optical artefacts to the emission.