@article {46772, title = {Hexaaminobenzene derived two-dimensional polymer supercapacitor with high specific capacitance and energy density}, journal = {ACS Applied Energy Materials}, volume = {3}, year = {2020}, month = {JUL }, pages = {6352-6359}, type = {Article}, abstract = {

Recent research interest has been shifted toward energy storage devices, especially supercapacitors, which provide high specific power and long cycle life. In this context, two-dimensional organic polymers are a class of versatile materials found to be useful in energy storage applications. However, the performance is not promising due to the low capacitance, energy density, and cyclic stability. Here, we report a two-dimensional polymer derived from hexaaminobenzene and pyromellitic dianhydride and its excellent supercapacitor performance. The specific capacitance of the two-dimensional polymer is found to be 805 F g(-1) at 0.5 A g(-1) current density in galvanostatic charge-discharge, which is the highest among the organic twodimensional polymer and most of the carbon-based materials. The superior performance of the 2D-polymer compared to a model derivative (350 F g(-1) at 0.5 A g(-1) current density) points to the critical role of a 2D-platform to excel. The high energy density, excellent cyclic stability, and low self-discharge rate support the 2D-polymer supercapacitor as a promising candidate for futuristic applications.

}, keywords = {2D-polymer, energy density, Energy storage, hexaaminobenzene, supercapacitor}, issn = {2574-0962}, doi = {10.1021/acsaem.0c00569}, author = {Wakchaure, Vivek C. and Kottaichamy, Alagar R. and Nidhankar, Aakash D. and Ranjeesh, Kayaramkodath C. and Nazrulla, Mohammed A. and Thotiyl, Musthafa O. and Babu, Sukumaran S.} } @article {46833, title = {Self-assembled helical arrays for the stabilization of the triplet state}, journal = {Angewandte Chemie-International Edition}, volume = {59}, year = {2020}, month = {JUL}, pages = {13079-13085}, type = {Article}, abstract = {

Room-temperature phosphorescence of metal and heavy atom-free organic molecules has emerged as an area of great potential in recent years. A rational design played a critical role in controlling the molecular ordering to impart efficient intersystem crossing and stabilize the triplet state to achieve room-temperature ultralong phosphorescence. However, in most cases, the strategies to strengthen phosphorescence efficiency have resulted in a reduced lifetime, and the available nearly degenerate singlet-triplet energy levels impart a natural competition between delayed fluorescence and phosphorescence, with the former one having the advantage. Herein, an organic helical assembly supports the exhibition of an ultralong phosphorescence lifetime. In contrary to other molecules, 3,6-phenylmethanone functionalized 9-hexylcarbazole exhibits a remarkable improvement in phosphorescence lifetime (\>4.1 s) and quantum yield (11 \%) owing to an efficient molecular packing in the crystal state. A right-handed helical molecular array act as a trap and exhibits triplet exciton migration to support the exceptionally longer phosphorescence lifetime.

}, keywords = {carbazole, helicity, phenylmethanone, ultralong phosphorescence, waveguiding}, issn = {1433-7851}, doi = {10.1002/anie.202005105, Early Access Date = JUN 2020}, author = {Nidhankar, Aakash D. and Goudappagouda and Kumari, Divya S. Mohana and Chaubey, Shailendra Kumar and Nayak, Rashmi and Gonnade, Rajesh G. and Kumar, G. V. Pavan and Krishnan, Retheesh and Babu, Sukumaran Santhosh} } @article {47078, title = {Aggregation-induced phosphorescence of an anthraquinone based emitter}, journal = {Organic \& Biomolecular Chemistry}, volume = {19}, year = {2021}, month = {FEB }, pages = {1004-1008}, type = {Article}, abstract = {

Room temperature phosphorescence (RTP) of metal-free organic molecules is a hot topic of current research interest. RTP can be enhanced through aggregation, crystallization, and the support of polymers and host-guest assemblies. The characteristics of highly phosphorescent aggregates formed from conventional chromophores make them ideal candidates for many potential applications. In this direction, we focused on the aggregation-induced phosphorescence of an anthraquinone derivative AqC6 in solution and in crystal state. The weakly emissive dilute solution exhibits a tunable emission with enhanced intensity and room temperature phosphorescence by increasing the concentration and solvent-antisolvent combination. The enhanced phosphorescence of crystals has been recreated in the solution by making use of aggregation. Interestingly, the support of PMMA enabled AqC6 to achieve enhanced processability, phosphorescence lifetime (174 ms) and quantum yield (5\%).

}, issn = {1477-0520}, doi = {10.1039/d0ob02505d}, author = {Goudappagouda and Nidhankar, Aakash D. and Nayak, Rashmi A. and Babu, Sukumaran Santhosh} } @article {47417, title = {Efficient metal-free organic room temperature phosphors}, journal = {Chemical Science}, volume = {12}, year = {2021}, month = {MAR}, pages = {4216-4236}, type = {Review}, abstract = {

An innovative transformation of organic luminescent materials in recent years has realised the exciting research area of ultralong room-temperature phosphorescence. Here the credit for the advancements goes to the rational design of new organic phosphors. The continuous effort in the area has yielded wide varieties of metal-free organic systems capable of extending the lifetime to several seconds under ambient conditions with high quantum yield and attractive afterglow properties. The various strategies adopted in the past decade to manipulate the fate of triplet excitons suggest a bright future for this class of materials. To analyze the underlying processes in detail, we have chosen high performing organic triplet emitters that utilized the best possible ways to achieve a lifetime above one second along with impressive quantum yield and afterglow properties. Such a case study describing different classes of metal-free organic phosphors and strategies adopted for the efficient management of triplet excitons will stimulate the development of better candidates for futuristic applications. This Perspective discusses the phosphorescence features of single- and multi-component crystalline assemblies, host-guest assemblies, polymers, and polymer-based systems under various classes of molecules. The various applications of the organic phosphors, along with future perspectives, are also highlighted.

}, issn = {2041-6520}, doi = {10.1039/d1sc00446h}, author = {Nidhankar, Aakash D. and Goudappagouda and Wakchaure, Vivek C. and Babu, Sukumaran Santhosh} } @article {47761, title = {Donor-acceptor based solvent-free organic liquid hybrids with exciplex emission and room temperature phosphorescence}, journal = {Chemical Communications}, volume = {58}, year = {2022}, month = {FEB }, pages = {1998-2001}, type = {Article}, abstract = {Solvent-free organic liquids are well-known for their excellent luminescence features. Hence, the recent developments in this area have marked them as potential emitters with high quantum yield and enhanced processability. The support of an available liquid matrix enables doping to deliver hybrid liquids with intriguing luminescence features. In this direction, we report solvent-free liquid donor-acceptor pairs with exciplex emission and room temperature phosphorescence at very low acceptor loading. The underlying weak intermolecular interactions have been revealed by 2D NMR techniques and theoretical calculations. The formation of large-area thin films by exciplex and phosphorescent liquid hybrids will encourage the development of scalable lighting and display materials.}, issn = {1359-7345}, doi = {10.1039/d1cc07082g}, author = {Wakchaure, Vivek Chandrakant and Veer, Sairam D. and Nidhankar, Aakash D. and Goudappagouda and Nayak, Rashmi and Asokan, Kiran and Ravindranathan, Sapna and Babu, Sukumaran Santhosh} } @article {48790, title = {Luminescent 3D printed poly(lactic acid) nanocomposites with enhanced mechanical properties}, journal = {Polymer Engineering and Science}, volume = {63}, year = {2023}, month = {JUL}, pages = {2059-2072}, type = {Article}, abstract = {

The three-dimensional (3D) printing of functional composite materials has gained tremendous interest in recent years. Nevertheless, research on 3D printing of luminescent composite materials is very limited, and the mechanical properties of such 3D-printed composites are poor. Herein, we report the preparation and characterization of a poly(lactic acid) (PLA) composite that, when 3D printed, exhibits enhanced toughness and high solid-state fluorescence quantum yield. Incorporation of only 1 wt\% pyrene butyric acid modified cellulose nanofibers (PBA-m-CNF) and l0 wt\% thermoplastic polyurethane (TPU) into PLA led to 223\% increase in toughness and 21\% increase in tensile modulus of PLA. Scanning electron microscopy (SEM) and X-ray microcomputed tomography (mu-CT) analysis of the fractured cross-sections of 3D printed composites revealed a ductile failure mode. The PLA/PBA-m-CNF1/TPU10 3D printed composite also exhibited a high solid-state fluorescence quantum yield of 38.35\%. To the best of our knowledge, this is the first report to show both enhanced mechanical properties and high solid-state fluorescence emission for 3D printable PLA. Such functional PLA composites could have potential applications in the fabrication of complex-shaped sensors, optical light pipes, etc.

}, keywords = {3D printing, Composite, fluorescence, Nanocellulose, poly(lactic acid), toughness}, issn = {0032-3888}, doi = {10.1002/pen.26345}, author = {Kothavade, Premkumar Anil and Yadav, Prashant and Nidhankar, Aakash D. and Torris, Arun and Pol, Harshawardhan and Kafi, Abdullah and Bateman, Stuart and Sukumaran, Santosh Babu and Shanmuganathan, Kadhiravan} }