Optical characterization and modeling of the lead chalcogenide quantum dot solar cell: A rational approach to device development and multiple exciton generation

Solar cells developed from quantum dot (QD) films are promising both for their ease of manufacture and for their potential enhanced photon conversion efficiencies. Schottky junction solar cells in particular produce very high photocurrents (25-35 mA/cm2) and with internal quantum efficiencies in excess of 80% in the visible and UV regions of the spectrum; but we have not yet observed a clear indication of MEG-enhanced photocurrent. Weak open circuit voltages limit efficiency in these devices. With small QDs, ZnO heterojunctions can both improve stability and device efficiency (via open circuit voltage), allowing us a new avenue to search for improved efficiency both with and without MEG. Optical characterization of our devices allows us to intelligently design devices, and understand current limitations. Therefore, we believe that performing optical modeling of devices for a range of QD sizes will help us to understand MEG mechanisms and efficiency.