No abstract

Organic field-effect transistors were fabricated with pentacene as the active material and a ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) as the gate insulator. As-prepared devices showed normal p-type transistor operation. The ON-and OFF-states could be written to the device by applying appropriate voltages to the gate with respect to short-circuited source and drain electrodes. The devices exhibited excellent memory retention properties.

Dye-sensitized solar cells (DSCs) are proved to be one among the best photovoltaic approach for harnessing indoor/artificial light. Herein, we report two new molecularly engineered cost-effective metal-free carbazole based D-π-A...

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, HBT-Fl1 and HBT-Fl2, we herein report the first efficient zwitterionic ESIPT lasing material (HBT-Fl2). The zwitterionic ESIPT HBT-Fl2 not only shows a remarkably low solid-state amplified spontaneous emission (ASE) threshold of 5.3 μJ/cm2 with an ASE peak at 609 nm but also exhibits high ASE photostability. Coupled with its substantially large Stokes shift (≈236 nm ≈10,390 cm–1) and an extremely small overlap of excited-state absorption with ASE emission, comprehensive density functional theory (DFT) and time-dependent DFT studies reveal the zwitterionic characteristics of HBT-Fl2. In opposition to conventional ESIPT with π-delocalized tautomerism as observed in analogue HBT-Fl1 and parent HBT, HBT-Fl2 instead shows charge redistribution in the proton transfer through the fluorene conjugation. This structural motif provides a design tactic in the innovation of new zwitterionic ESIPT materials for efficient light amplification in red and longer-wavelength emission.

No abstract

No abstract

No abstract

No abstract