@article {48670, title = {High open-circuit voltage in lead sulfide quantum dot solar cells via solution-phase ligand exchange with low electron affinity cadmium halides}, journal = {JOURNAL OF MATERIALS CHEMISTRY A}, volume = {11}, year = {2023}, month = {AUG}, pages = {17282-17291}, type = {Article}, abstract = {

The deployment of colloidal quantum dots (QDs) in building high-performance solar cells and other optoelectronic applications relies on the passivation of unsaturated surface atoms through ligand engineering to attain a trap-free energy bandgap and strong QD coupling while maintaining the quantum confinement effect. Despite major advancements in surface passivation strategies, the open circuit voltage (V-oc) of lead sulfide (PbS) QD solar cells is limited by undesirable sub-bandgap states and high-bandtail states. The most advanced solution-phase ligand exchange strategy for PbS QDs depends on lead halide ligands, which improved the photocurrent and fill factor in QD solar cells significantly, but only an incremental change in V-oc is observed. Here we showcase a solution-phase hybrid ligand passivation strategy for PbS QDs using shallow electron affinity cadmium halide and thiol ligands. The cadmium halide ligand treatment results in the sub-monolayer substitution of surface Pb atoms by Cd atoms. The photophysical properties of QDs improve significantly to show intense band edge emission, diminished trap emission and reduced Urbach tail states. The photovoltaic devices built using cadmium halide-treated QDs show low reverse saturation current, which helps to attain a record 0.7 V V-oc (for a 1.28 eV bandgap) and 12.3\% PCE.

}, issn = {2050-7488}, doi = {10.1039/d3ta02191b}, author = {Dambhare, Neha V. and Biswas, Arindam and Sharma, Anjali and Shinde, Dipak Dattatray and Mahajan, Chandan and Mitra, Anurag and Rath, Arup K.} } @article {49639, title = {High-performance photodetector from p-n junction of vertically aligned SnS2 and reduced graphene oxide}, journal = {ACS Applied Electronic Materials}, volume = {6}, year = {2024}, month = {SEP}, pages = {6965-6973}, type = {Article}, abstract = {

Semiconducting 2D transition metal dichalcogenides (TMDC) became very popular in photodetection due to their high mobility and high rate of generating electron and hole pairs. Over the past decade, MoS2 and WS2 became the most popular TMDC for several applications. On the other hand, due to the complex synthesis process compared to MoS2 and WS2, SnS2 became a less popular 2D material for photodetection. We synthesized vertically aligned SnS2 flakes by a chemical vapor deposition (CVD) process with three temperature zones with controlled argon (Ar) gas flow. Pristine SnS2-based devices are not very suitable for photodetection applications because of their low photo-to-dark current ratio (I ph /I (dark) ), high response time, and low stability. So, they need to be decorated with oppositely doped materials. We decorated pristine SnS2-based devices with rGO nanoparticles, which significantly increased the device{\textquoteright}s performance. We found a high responsivity (R) of 1.33 A/W, detectivity (D) of 6.95 x 10(11) Jones, I ph /I dark of 102, and a rise time of 0.241 ms (fall time of 1.318 ms) with the rGO decorated SnS2-based device.

}, keywords = {2D-SnS2, CVD, p-njunction, photodetector, rGO}, doi = {10.1021/acsaelm.4c01311}, author = {Das, Chayan and Kumar, Suresh and Dambhare, Neha V. and Kumar, Mahesh and Rath, Arup K. and Sahu, Satyajit} }