Dark current suppression in quantum dot solar cells through interfacial engineering

Abstract

Thin interfacial insulators made of materials such as Lithium Fluoride or various oxide compositions have been shown to improve open circuit voltage and fill factor in quantum dot solar cells primarily due to the lowering of surface recombination leakage and the prevention of metal penetration into the active layer. In this paper, we highlight that, besides the above mentioned benefits, the thin interfacial barrier could also significantly lower the dark current leakage and hence could provide an additional performance improvement when dark current leakage is dominant. We computationally explore how the dark current suppression could affect the cell characteristics as a function of interfacial layer thickness, carrier mobility, and the recombination lifetime. We show that an ultrathin (~10A) interfacial layer could significantly improve cell efficiency when carrier mobility is relatively high and the dark current is significantly suppressed due to the presence of a tunneling barrier.