This comprehensive review surveys the up-to-date development of aggregation-induced emission/aggregation-induced emission enhancement (AIE/AIEE) active naphthalimide (NI)-based smart materials with potential for wide and real-world applications and that serves as a highly versatile building block with tunable absorption and emission in the complete visible region. The review article commences with a precise description of the importance of NI moiety and its several restricted area of applications owing to its aggregation caused quenching (ACQ) properties, followed by the discovery and importance of AIE/AIEE-active NIs. The introduction section tracked an overview of the state of the art in NI luminogens in multiple applications. It also includes a few mechanistic studies on the structure-property correlation of NIs and provides more insights into the condensed-state photophysical properties of small aggregation-prone systems. The review aims to ultimately accomplish current and forthcoming views comprising the use of the NIs for the detection of biologically active molecules, such as amino acids and proteins, recognition of toxic analytes, fabrication of light emitting diodes, and their potential in therapeutics and diagnostics.

The observation of unusual aggregation-induced emission enhancement (AIEE) phenomenon in the deep red wavelength region, dual state emission, and intramolecular charge transfer of dibenzofulvene (DBF) derivatives are described. These consist of a series of newly synthesized donor–acceptor based monosubstituted molecules (DT1, DT2, DP1, and DP2) with their cores comprising DBF molecules. Two luminogens with thiophene-substituted at the ninth position of DBF, viz. DT1 and DT2, displayed AIEE with predominant J-type aggregation due to the effect of intramolecular planarization and formation of nanoparticles in the aggregated state. In the DP1 and DP2 luminogens an extra phenyl ring was inserted at the ninth position of DBFs (between thiophene and DBF) that resulted in a blueshift (∼60 nm) as compared to the DT derivatives and exhibited a unique dual state emission with good quantum yields. This additional phenyl moiety reduces the effective conjugation length toward 2,1,3-benzothiadiazole from DBF and simultaneously interrupts the head to tail interaction and also prevents the J-type aggregation. All the four luminogens exhibited distinctive solvent-dependent photoluminescence (PL) behavior (solvatochromism) because of the efficient intramolecular charge transfer. The DT2 and DP2 luminogens showed heavy atom effect due to the presence of two bromine atoms.

A nonvolatile “resistive random access memory” (ReRAM) device is reported with a series of four conjugated polymers (CPs) containing poly­[2,7-(9,9′-dioctyl­fluorene)-co-N-phenyl-1,8-naphthalimide (PFO–NPN) as donor and acceptor, respectively. A single layer, thin film of PFO–NPN copolymer that is sandwiched between indium tin oxide (ITO) and aluminum shows bistable property with a remarkably high I on/I off ratio of 108. The charge transport of the polymer is studied by fitting I–V curves with various conduction models to realize that the trap charge limited current (TCLC) assists in switching and exhibiting bistable property of the memory device. Theoretical calculations were also performed on the polymer to elucidate the presence of traps on the carbonyl oxygen atoms of NPN moiety. In addition, ReRAM properties like I on/I off ratio and write voltage were also tuned by changing the concentration of the acceptor moiety. Four different copolymers of acceptor concentrations (5%, 10%, 35%, and 50%) with respect to donor concentrations were characterized as a memory device. The device with high acceptor concentration (50%) showed the lowest I on/I off ratio (103) and write voltage (0.8 V). It was also observed experimentally that the I on/I off ratio and write voltage decrease sequentially with an increase in the acceptor concentration, thereby providing flexibility in tuning the memory parameters by allowing a molecular level change in the active material. The optical studies were performed to elucidate the mechanism of the tunable memory characteristic of the polymer, and the results reveal that the tunability is achieved due to the variation in the injection barrier and the strength of ICT for the different polymers.

The concurrent enhancement of the short-circuit current (JSC) and open-circuit voltage (VOC) is a key problem in the preparation of efficient organic solar cells (OSCs). In this paper, we report...

White organic/polymer light emitting diode (WOLED/WPLED) processed from solution has attracted significant research interest in recent years due to their low device production cost, device flexibility, easy fabrication over large area including roll to roll and ability to print in various designs and shapes providing enormous design possibilities. Although WOLEDs fabricated using solution process lack their thermally evaporated counterparts in terms of device efficiency, remarkable progress has been made in this regard in recent years by utilizing new materials and device structures. In the present review, we have summarized and extrapolated an excellent association of old and modern concept of cost-effective materials and device structure for realization of white light. In particular, this article demonstrated and focused on design, and development of novel synthesis strategy, mechanistic insights and device engineering for solution process low cost WOLEDs device. Herein, an overview of the prevailing routes towards white light emitting devices (WLEDs) and corresponding materials used, including polymer based WLED, small molecules emitters based thermally activated delayed fluorescence (TADF), perovskite light-emitting diodes (PeLEDs) and hybrid materials based LEDs, color down-converting coatings with corresponding best efficiencies ever realized. We presume that this exhaustive review on WLEDs will offer a broad overview of the latest developments on white SSL and stonework the approach en route for innovations in the immediate future.