@article { ISI:000323241100045, title = {Enhanced hole carrier transport due to increased intermolecular contacts in small molecule based field effect transistors}, journal = {ACS Applied Materials \& Interfaces}, volume = {5}, number = {15}, year = {2013}, month = {AUG}, pages = {7086-7093}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Small molecules and oligomers can be synthesized with very high purity and precise molecular weights, but they often do not form uniform thin films while processed from solution. Decreased intermolecular contacts between the small molecules are another disadvantage. To increase the intermolecular contacts in small molecules, we have chosen i-indigo, as one of the conjugated molecular units. The electron poor i-indigo has been connected with electron rich triphenylamine to synthesize a donor-acceptor-donor type small molecule. The propeller shaped triphenylamine helps to increase the solubility of the small molecule as well as isotropic charge transport. The intermolecular spacing between the molecules has been found to be low and did not vary as a function of thermal annealing. This implies that the intermolecular contacts between the small molecules are enhanced, and they do not vary as a function of thermal annealing. Organic field effect transistors (OFET) fabricated using a small molecule exhibited a hole carrier mobility (mu) of 0.3 cm(2)/(V s) before thermal annealing. A marginal increase in mu was observed upon thermal annealing at 150 degrees C, which has been attributed to changes in thin film morphology. The morphology of the thin films plays an important role in charge transport in addition to the intermolecular spacing that can be modulated with a judicious choice of the conjugated molecular unit.

}, keywords = {hole mobility, i-indigo, organic field effect transistor, quadrupole interaction, small molecules, triphenylamine}, issn = {1944-8244}, doi = {10.1021/am401379a}, author = {Dharmapurikar, Satej S. and Arulkashmir, Arulraj and Das, Chayanika and Muddellu, Pooja and Krishnamoorthy, Kothandam} } @article {46937, title = {Effect of aromatic rings and substituent on the performance of lithium batteries with rylene imide cathodes}, journal = {ChemElectroChem}, volume = {7}, year = {2020}, month = {MAR }, pages = {1160-1165}, type = {Article}, abstract = {

Rylene imides (RIs) are attractive organic battery materials because of the inherent modularity of the molecules. While strong aggregation of RIs is disadvantageous for fast lithium-ion transport in the organic active material, decreasing the solubility of the RIs in battery electrolytes is essential to avoid performance fading. Therefore, the design and synthesis of RIs for lithium batteries is a non-trivial task that must, among other considerations, balance lithium-ion transport in the solid material vs. low solubility by controlling aggregation and packing. We have chosen triphenylamine (TPA) as a substituent which disrupts the aggregation but maintains a low solubility due to increased aromaticity of TPA. We have synthesized three RIs with one, two, and four aromatic units in the core. All of them showed stable specific capacity over 300 charge-discharge cycles. The batteries also showed specific capacities close to their theoretical capacities with 97-99 \% coulombic efficiency. The maximum specific energy and specific power were 197 mWh g(-1) and 37 mW g(-1), respectively.

}, keywords = {lithium-ion batteries, organic cathode material, rylene imides, solubility, triphenylamine}, issn = {2196-0216}, doi = {10.1002/celc.202000118}, author = {Aher, Jagdish and Graefenstein, Alexander and Deshmukh, Gunvant and Subramani, Kumar and Krueger, Bastian and Haensch, Mareike and Schwenzel, Julian and Krishnamoorthy, Kothandam and Wittstock, Gunther} } @article {46984, title = {Tuning phosphorescence features of triphenylamines by varying functional groups and intermolecular interactions}, journal = {Dyes and Pigments}, volume = {173}, year = {2020}, month = {FEB}, pages = {107931}, type = {Article}, abstract = {

Organic room temperature phosphorescent materials are known for their synthetic feasibility, tunable phosphorescence wavelength and lifetime, etc. Hence new design strategies have been applied on various fluorophores to improve phosphorescence features. Among those, triphenylamines are phosphorescence active due to the presence of nitrogen atom, propeller molecular structure, and intermolecular interactions in the crystal state. Here we have studied the room temperature phosphorescence of a series of triphenylamines with various functional groups. Detailed studies have shown that the phosphorescence can be fine-tuned by functional group modification. A long phosphorescence lifetime around 100 ms at room temperature in air can be achieved by the interplay of intermolecular interactions, singlet-triplet energy gap and extent of intersystem crossing using functional group variation. Interestingly, an exciplex assisted ultralong phosphorescence lifetime (more than 20 times) is observed for a combination of triphenylamine and naphthalenemonoimide in air.

}, keywords = {Exciplex, fluorescence, Phosphorescence, triphenylamine}, issn = {0143-7208}, doi = {10.1016/j.dyepig.2019.107931}, author = {Goudappagouda and Asokan, Kiran and Nayak, Rashmi and Krishnan, Retheesh and Babu, Sukumaran Santhosh} }