Functionalization of Graphene Oxide Films with Au and MoO_x Nanoparticles as Efficient p‐Contact Electrodes for Inverted Planar Perovskite Solar Cells

Abstract

A graphene oxide (GO) film is functionalized with metal (Au) and metaloxide (MoO x ) nanoparticles (NPs) as a hole-extraction layer for highperformance inverted planar-heterojunction perovskite solar cells (PSCs). These NPs can increase the work function of GO, which is confirmed with X-ray photoelectron spectra, Kelvin probe force microscopy, and ultraviolet photoelectron spectra measurements. The down-shifts of work functions lead to a decreased level of potential energy and hence increased V oc of the PSC devices. Although the GO-AuNP film shows rapid hole extraction and increased V oc , a J sc improvement is not observed because of localization of the extracted holes inside the AuNP that leads to rapid charge recombination, which is confirmed with transient photoelectric measurements. The power conversion efficiency (PCE) of the GO-AuNP device attains 14.6%, which is comparable with that of the GO-based device (14.4%). In contrast, the rapid hole extraction from perovskite to the GO-MoO x layer does not cause trapping of holes and delocalization of holes in the GO film accelerates rapid charge transfer to the indium tin oxide substrate; charge recombination in the perovskite/GO-MoO x interface is hence significantly retarded. The GO-MoO x device consequently shows significantly enhanced V oc and J sc , for which its device performance attains PCE of 16.7% with great reproducibility and enduring stability.

All‐Inorganic CsPbX3 Perovskite Solar Cells: Progress and Prospects

“…transporting layer (ETL) or hole transporting layer (HTL); [182,183] Liu et al used aZ nO@C 60 bilayer as the ETL and NiO as the HTL in an inverted cell which demonstrated high electron extraction efficiency and low leakage loss. [76] Theresulting cell yielded asPCE of around 12 %and rfV OC = 1.09 V. Yane tal.…”

Interfacial Modification in Organic and Perovskite Solar Cells

“…[1d] So far, there have been a large number of efforts devoted to obtaining effective surface trap passivation through incorporating interlayers in PSCs with p‐i‐n or n‐i‐p device structures. For HTLs, in addition to inorganic materials (NiO x , CuSCN, MoO x , etc. ), organic counterparts of both small molecules and polymers have been widely used in PSCs with tunable work functions and surface properties.…”

Graphene‐Based Materials in Planar Perovskite Solar Cells

“…Graphene‐based materials have been used as modifiers in ETLs and HTLs, but they have also been directly utilized as CTLs in planar PSCs. [ 135,136 ] Research articles on the direct utilization of graphene as ETL are hardly reported in the regular planar PSCs, whereas there are many important research works on the direct utilization of graphene as HTL in inverted planar PSCs. This can be attributed to the reason that the Fermi level of graphene is close to the valence band of perovskite, so graphene films are more suitable for hole extraction.…”