A series of π-extended quinolines with D−π–A–D and D−π–A–A architectures were designed and synthesized via the Sonagashira cross-coupling reaction to serve as ambipolar organic semiconductors for use in C–FET. Ambipolar mobilities were observed for methoxy- and tert-butyl group-substituted compounds. Among the molecules studied, π-extended methyl 2-(4-methoxyphenyl)-6-((4-methoxyphenyl)­ethynyl)­quinoline-4-carboxylate with D−π–A–D architecture exhibited high ambipolar transistor characteristics with hole and electron mobilities of 0.10 and 0.05 cm2/V s, respectively. The good charge carrier mobilities are supported by an electron-donating methoxy group with high highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, extensive π-conjugation, and better self-assembly. Organic field-effect transistor (OFET) devices were fabricated using the spin-coating technique with BGTC configuration. By employing the postannealing technique, self-assembled crystalline films were obtained as depicted by scanning electron microscopy (SEM). These compounds can find potential applications in organic light-emitting transistors, sensors, and logic circuits.

A series of metal-free porphyrin molecules with functionalized triarylamines at the meso-position are designed and synthesized. All the functionalized porphyrins possess good thermal stability and high decomposition temperatures over 422 °C and also exhibited electrochemical reproducibility. The calculated ionization potentials are in the range of −5.01 to -5.42 eV, and electron affinity levels are in between −2.47 and −2.91 eV, which supports stable charge ejection. Organic fieldeffect transistor (OFET) devices with bottom-gate/top-contact architecture are fabricated by a solution-processable technique. OFETs with an active layer of porphyrin with electron-accepting trifluorophenyl groups gave the highest charge carrier mobility of 4.4 cm 2 /Vs and an on/off ratio of 10 7 . The obtained results indicate these compounds to be efficient hole-transporting materials. This research work presents the highest mobilities of the porphyrins reported until now.

Integration of devices for their efficiency is considered to be the future goal of organic electronics. One such highly integrated device which combines the properties of both the organic field-effect transistor and organic light-emitting diodes are the organic light-emitting transistors (OLETs). These devices are exceedingly preferred for their enhanced properties/performance in terms of both mobility and luminescence. It becomes a singly stacked device enabling the integration of both a transistor and a light emitter in the same. Although it is a budding field of organic electronics, limited literature is available which keeps on increasing due to its high advantages in many applications. This review gives a brief knowledge of the OLETs being fabricated recently using different materials and the developments in device fabrications. The review looks through an organic chemist's perspective, digging into many ways through which an OLET material can be designed and characterized. It also looks through the developments made in the device architecture during the years enabling better performance through many different ways.

Phenanthro[9,imidazole is synthesized by employing Radziszewski method and further functionalized through palladium catalyzed Suzuki cross-coupling reaction. Solution processable organic field-effect transistors (OFETs) are assembled in bottom gate-top contact architecture. A binary solvent system comprising of chloroform/toluene in the ratio of 1/1 is preferred for the deposition of active semiconducting layer. The fabricated devices demonstrated excellent p-type characteristics with a good mobility, high ON/OFF ratio of 10 9 and a minimum threshold voltage of À 4.5 V. Computational investigations indicted proper charge separation of the energy levels for the phenanthro[9,10-d] imidazole containing nitro group. Frontier molecular orbitals and the packing patterns obtained from computational studies suggest an efficient band gap for better device operation. The ordered morphologies of the molecules obtained from SEM analysis prove to be beneficial in the OFET performance. The photophysical, electrochemical and thermal properties of the molecules are studied in detail. The research work majorly emphasized on structural designing of the phenanthro[9,10-d]imidazoles for potential applications in organic devices.

Donor-Acceptor systems are highly appreciated in the field of organic memory devices due to their efficient charge transport within the systems. In this work, we have designed and synthesized a DÀ πÀ A system constituting esterflanked quinolines and functionalized triarylamines (TAA) through a single-step cross-coupling reaction to fabricate memory devices via Write-Once Read-Many times (WORM) non-volatile memory. Structure-property relationships are reconnoitered for these conjugated DÀ πÀ A systems through a series of UV, fluorescence, XRD, DFT, and memory characterizations. The UV and CV data show efficient charge transfer with intramolecular charge transfer occurring at 407-417 nm and a short band gap of 2.56-2.65 eV. An enhancement in the resistive switching behavior of the memory devices is observed for the compounds with simple TAA-quinoline and tert-butylphenyl substituted TAA and fluorophenyl substituted quinoline due to balanced charge distribution in the compounds. This enhanced switching induces an on/off ratio of 10 3 by generating a highly ordered arrangement in the thin films. The HOMO, LUMO levels, and the ESP images together estimate a charge transfer and charge trapping as the plausible mechanism for the solution-processable WORM memory devices. The longer retention time (10 3 s) and lower threshold voltages (À 1.21-À 2.12 V) of the devices makes them intriguing compounds for memory applications.