Quantum dot - organic hybrid systems in photovoltaic devices
Amlan J. Pal
Indian Association for the Cultivation of Science, Department of Solid State Physics, Kolkata, India
Building 24, Room Alpha
May 20th, 2011
The talk will show that core-shell organic-inorganic hybrid nanoparticles can be grown via electrostatic interaction between a functionalized inorganic core and ionic organic-dye molecules.1 In hybrid core-shell nanoparticle systems, photoinduced electron transfer takes place from the semiconducting core to an organic-shell. Dissociation of excitons hence occurs as a spontaneous manner. With the hybrid core-shell nanoparticles, we have fabricated devices so that exciton-dissociation can occur and finally yield photocurrent in the external circuit of photovoltaic solar cells. Here, following the electron transfer, electrons flow through the organic molecules and holes, left in the nanoparticles, move through the hole-transporting polymer to the opposite electrodes to yield a photovoltaic short-circuit current. From control experiments with ZnS nanoparticles in the core, we have substantiated the role of CdSe nanoparticles in light-harvesting and charge-generation.
Moreover, we have provided a route to extend the spectral window of hybrid solar-cells towards near-IR region. Photovoltaic devices based on PbS quantum dots that absorb in the near-IR region have so far remained inactive in the region due to an unfavorable energy band-diagram. It did not allow dissociation of excitons generated in PbS. We show that with assistance from a strong electron-acceptor, these excitons can be dissociated to obtain near-IR active photovoltaic solar cells.
Microelectronics and emerging technologies
Sensors and instrumentation