Hybrid materials of upcycled Mn3O4 and reduced graphene oxide for a buffer layer in organic solar cells

Abstract Mn 3 O 4 on reduced graphene oxide (r-GO) was easily synthesized by upcycling process of wasting manganese ions which were generated during oxidation reaction from graphite to GO. The yellow-brown GO suspension under acid media before neutralization immediately became black precipitates when the suspension was titrated into the concentrated NaOH solution. The method could convert the wasting manganese ions up to ∼91 wt% to Mn 3 O 4 to optimize work function in a hole transport layer (HTL) for organic solar cells. The hybrid materials exhibited an ideal electronic structure suitable for HTL, leading to the excellent power conversion efficiency of ∼3.23%.