Research Projects

The theme of the project is to develop semiconductor nanocrystal (NC)-molecule assemblies for phototocatalysis and use the understanding gained therefrom to explore newer areas of triggering biologically relevant processes by NCs and developing qubits based on them. The major part of the proposal comprises photosensitization of molecular cocatalysts, developed in the group of the Co-PI, by NCs prepared in the group of the PI. The key process here is photoinduced electron transfer (PET) from the NCs to the cocatalysts. PI’s group has the expertise to investigate the ultrafast dynamics involved in the process, which would be the primary parameter on which better photosensitizers would be designed collaboratively by the two groups. The major instrument to be used in this part is ultrafast transient absorption, in conjunction with femtosecond optical gating (FOG), time correlated single photon counting (TCSPC) and also fluorescence correlation spectroscopy (FCS), especially fluorescence lifetime correlation spectroscopy (FLCS). In this part, the emphasis would be on the shorter time regime of FCS, which gives an idea about reaction kinetics. Slow back electron transfer dynamics will be investigated using flash photolysis. The PI’s group has expertise in these techniques. The instruments are available in IIT Bombay In addition to photosensitization, direct photocatalysis by the NCs will be attempted. The two groups have already collaborated to get interesting preliminary results on hydrogen evolution reaction (HER) and carbon dioxide reduction reaction (CO2rr), photosensitized by NC-cocatalyst assemblies. So, the initial experiments will focus on these, but then photocatalysis of other important organic reactions will also be attempted. The NCs to be used will be of Cd chalcogenides to start with, but the goal is to develop systems based on more environment-friendly materials like InP, CuInS2.AgInS2, AgInSe etc. and perovskites, especially Pb-free ones. The effect of doping by ions like Cu+/Ag+ etc., formation of shells by materials like ZnS and also the size and shape of the NCs, on photosensitization/ direct photocatalysis by them, will be investigated. Taking a cue from these experiments, biological processes involving electron transfer will be studied. The initial plan is to photosensitize redox enzyme catalysis by the NCs. Other than electron transfer, triplet-triplet energy transfer will be explored. This is where the perovskite NCs are going to find a major application, by virtue of their microsecond lifetimes. On a different note, semiconductor NC-organic molecule assemblies are becoming increasingly interesting for applications in producing spin qubit pairs (SQPs), which are proposed to have important implications in the upcoming area of quantum computing. The process involved is PET, line in photocatalysis, but from molecule to NC. This aspect will be probed using the time resolved spectroscopic and microscopic techniques. The project aims to go from the realm of fundamental research to possible translation. To this effect, a prototype for photo-driven HER will be developed, based on the optimized engineered nanostructures developed in the course of the project. The Co-PI’s group has existing expertise in this aspect, which will be exploited. To summarize, the goal of the project is to take the ongoing collaborative study on photosensitized HER/CO2rr to completion and make use of the understanding generated in the process to open up newer applications as discussed above.