@article {46731,
	title = {Unsymmetrical squaraine dyes for dye-sensitized solar cells: position of the anchoring group controls the orientation and self-assembly of sensitizers on the TiO2 surface and modulates its flat band potential},
	journal = {Journal of Physical Chemistry C},
	volume = {124},
	year = {2020},
	month = {AUG},
	pages = {18436-18451},
	type = {Article},
	abstract = {<p>The position of the anchoring group is systematically changed with a series of alkyl group wrapped donor-acceptor-donor (D-A-D) based squaraine dyes, 4-SQ to 7-SQ, for the use in dye-sensitized solar cells (DSSCs). By this approach, the orientation as well as the self-assembly of the sensitizers can be controlled on the semiconducting TiO2 surface. All of the dyes functionalized with hydrophobic alkyl groups at sp(3)-C and N atoms of the indoline units that is far away from the TiO2 surface to control the self-assembly of dyes and passivate the surface. Controlling both the orientation as well as the self-assembly of the sensitizers synergistically enhances the V-oc of the DSSC device by imparting the dipole moment on the TiO2 surface and minimizing the interfacial charge recombination process of electrons from TiO2 to the oxidized electrolyte, respectively. Further, the presence of a meta-carboxyl group with respect to the N atom of the indoline donor unit for the dyes 4-SQ and 6-SQ makes them nonconductive for the charge injection process, which sheds light on the importance of through-space electron transfer for the device performance. Emission from the relaxed twisted state was found to be a deactivation pathway for 4-SQ on TiO2 and ZrO2, which revealed the importance of structural factors that promote spatial interaction between the sensitizer and metal oxide surface. Computational studies showed the systematic changes in the dipole moment for the sensitizers 4-SQ, 5-SQ, and 6-SQ upon anchoring to the TiO2 surface. The DSSC device performance varied with the position of anchoring groups in the sensitizers. The DSSC device performance of 5-SQ indicates a J(sc) value of 11.35 mA cm(-2), V-oc of 0.698 V, and ff of 77\% corresponding to a power conversion efficiency of 6.08\% in the presence of 3 equiv of coadsorbent CDCA, which is nearly 1.5 times higher than 6-SQ (V-oc 0.7 V, J(sc) 7.76 mA cm(-2), ff 76\%, and eta 4.14\%) and 2.6 times higher than 4-SQ (V-oc 0.658 V, J(sc) 4.42 mA cm(-2), ff 78\%, and eta 2.28\%). IPCE studies revealed the importance of orientation for the charge injection and self-assembly of dyes, as devices with 5-SQ and 6-SQ as a sensitizer showed 94 and 77\% response at 578 nm, respectively, which correspond to the aggregated structure of the dye. Mott-Schottky and IPCE experiments showed that the orientation of sensitizers could modulate the V-oc due to the shift in the flat band potential of TiO2.</p>
},
	issn = {1932-7447},
	doi = {10.1021/acs.jpcc.0c05176},
	author = {Singh, Ambarish Kumar and Maibam, Ashakiran and Javaregowda, Bharathkumar H. and Bisht, Rajesh and Kudlu, Ashwath and Krishnamurty, Sailaja and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj}
}
@article {49933,
	title = {Supercooled liquid phases of luminescent zero dimensional metal halide hybrids},
	journal = {Journal of Physical Chemistry Letters},
	volume = {16},
	year = {2025},
	month = {SEP},
	pages = {9391-9400},
	type = {Article},
	abstract = {<p>
	Chemical design of metal halide hybrids (MHHs) with suppressed melting point (T-m) allows access to glassy phases from their liquid-melts. Thermal phase change (crystal-melt-glass) properties of glassy MHHs (with glass transition temperature T-g \&gt; room temperature) have been exploited for device applications. However, room temperature stable supercooled liquid (SCL) MHHs (with T-g \&lt; room temperature), originating from glass-SCL phase change, remain inaccessible. Here, a molecular design strategy is reported to access ambient stable, melt-processable, SCL multimetallic bromide hybrids (Mn2+,Cd2+; Mn2+,Zn2+; Benzyltributylammonium) with low T-g (15-16 degrees C), low T-m (90-100 degrees C), green luminescence, and high optical transparency. Structural, optical, thermal, and computational analyses highlight chemical design principles and support dopant (Mn2+) based luminescence. Rheological measurements confirm the SCL phase that shows thermal hysteresis and estimate relaxation time scales. This work provides a new material platform showcasing enhanced melt-processability for fabrication of moldable devices, unravelling chemical makeup-property correlation and expanding the material phase types of MHHs.</p>
},
	issn = {1948-7185},
	doi = {10.1021/acs.jpclett.5c01979},
	author = {Kumar Das, Deep and Marayathungal, Jumana Hasin and Palakkolil, Athira and Sarma, Dhritismita and Khan, Akram Aadil and Kumar, M. Praveen and Kudlu, Ashwath and Choudhary, Mahendra and Hathwar, Venkatesha R. and Pujala, Ravi Kumar and Mahata, Arup and Kundu, Janardan}
}
