Perovskite/Graphene Solar Cells without a Hole-Transport Layer

This study was conducted with the objective of improving the stability of perovskite solar cells by using the unique characteristics of graphene in order to facilitate the widespread application of such solar cells, for example, in multijunction devices. We consequently developed a new transfer method for graphene using vacuum lamination and, using graphene, successfully fabricated a perovskite solar cell that does not require a hole-transport layer. Initial stability tests indicated that the new device has better stability than a control perovskite solar cell using spiro-OMeTAD. Although the new solar cell design exhibited poorer cell performance than the control, we determined via modeling that its performance can be improved by modifying the interface state between perovskite and graphene or by modulating the work function of graphene.