Near-IR activity of hybrid solar cells: Enhancement of efficiency by dissociating excitons generated in PbS nanoparticles

Photovoltaic devices based on PbS nanoparticles remained inactive in the near-IR region due to a not-so-favorable energy band-diagram that does not allow dissociation of excitons generated in PbS. In this work, with the introduction of TiO2 nanostructures in the PbS-based hybrid system, we show an enhancement of photovoltaic performance in both visible and near-IR regions. The addition of TiO2 increases the power conversion efficiency from 0.006% to 0.12%. With the aid of energy band-diagram, we show that excitons generated in PbS even in the near-IR range can now become dissociated to yield photocurrent in the external circuit.