Hydrophobic Graphene Quantum Dots for Defect Passivation and Enhanced Moisture Stability of CH₃NH₃PbI₃ Perovskite Solar Cells

Abstract

Passivating the defects and grain boundaries (GBs) of perovskite films at the interface by interface engineering is a promising route to achieve efficient and stable perovskite solar cells (PSCs). Herein, a new type of graphene, that is, hydrophobic graphene quantum dots (HGQDs) containing amide linkages, which consist of carbonyl and dodecyl amine groups, is successfully used as a bifunctional interface modifier to engineer the interface of the perovskite/hole transport layer. A comprehensive characterization including X‐ray photoelectron spectroscopy, Fourier‐transform photocurrent spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, and space‐charge‐limited current measurements is performed to identify the underlying passivation mechanisms. It can be demonstrated that the HGQDs, due to the bifunctional groups containing N and O atoms, effectively passivate the uncoordinated Pb2+ ions at the perovskite film surface and GBs and consequently induce a lower trap state density. Moreover, HGQDs enhance the quality of the perovskite film which reduces the charge recombination at the interface. Therefore, the power conversion efficiency of PSCs treated with HGQDs is significantly increased from 16.00% to 18.30%, mainly based on the improved open‐circuit voltage and fill factor. Importantly, the HGQDs featuring hydrophobicity due to alkyl chains significantly enhance moisture stability.

Interfacial Engineering of a PCBM/AZO Electron Transport Bilayer for Efficient and Stable Inverted Perovskite Solar Cells

“…[33] Similarly, PZDI deposited atop the perovskite layer can prevent degradation of the perovskite layer and encourages reducing interfacial charge recombinations. [34][35][36] Therefore, the interfacial modification of PSC using passivation layers on top and beneath the perovskite layer can contribute to higher device performances by exhibiting favorable band alignments, better interfacial contact, and improved crystallinity. Further, the PCBM and Al-doped ZnO (AZO) were deposited over ITO/NiO x /MeO-2PACz/FACsRbP-bI 3 /PZDI thin films.…”

Recent progress on the use of graphene-based nanomaterials in perovskite solar cells

“…The hydrophilic and high acidic nature of PEDOT:PSS resulted in the destruction of the ITO electrode and perovskite, which reduced the stability and performance of PSCs. Khorshidi et al 236 used new types of hydrophobic GQDs (HGQDs) containing amide linkages and consisted of carbonyl and dodecyl amine groups as the bifunctional interface between the perovskite lm and HTL. The engineered PSCs' interface displayed a much-enhanced stability in ambient conditions.…”

Application of Quantum Dot Interface Modification Layer in Perovskite Solar Cells: Progress and Perspectives

“…The PCE obtained was 15.8%, which was a 35% improvement over the reference cell. In 2022, Khorshidi et al [102] applied hydrophobic GQDs (HGQDs) to PSCs. The amide groups contained within the HGQDs uncoordinated Pb 2+ ions to passivate the film surface and reduce the defect density, with a PCE of 18.30%.…”

“…At the same time, the hydrophobic alkyl group made the perovskite film impermeable to water, significantly improving stability. All details are displayed in Table 4 [100][101][102]. x QDs and used them as a modification interface layer.…”