Graphene-Assisted Zwitterionic Conjugated Polycyclic Molecular Interfacial Layer Enables Highly Efficient and Stable Inverted Perovskite Solar Cells

Abstract

As an effective strategy to achieve high performance and operational stability in perovskite solar cells (PSCs), numerous studies have been conducted to develop efficient charge transporting materials that possess desirable conductivity, carrier mobility, and stability. Among the great number of candidate materials, graphene has attracted significant attention owing to its remarkable optoelectrical properties and stability. Based on these advantages, in this study, a graphene-assisted electron transport layer (ETL) was developed through functionalization with an n-type semiconducting small molecule, perylene diimide amino N-oxide (PDINO), which simultaneously improved the performance and stability of PSCs. The PDINO-functionalized graphene ETL exhibited suitable energy-level alignment with enhanced carrier mobility, thus resulting in an enhanced power conversion efficiency of 21.2% for the inverted structured PSCs. Moreover, through the hydrophobic surface feature and barrier property of graphene and the π–π interaction of PDINO with the underlying layer of PSCs, notably improved operational stability was achieved using the developed functionalized graphene ETL.

Solution-processed two-dimensional materials for next-generation photovoltaics

“…1192 By formulating 2D material-based inks in solvents compatible with materials composing the PSCs, GRMs have been successfully integrated as both CTLs and interlayers, 1283 improving the charge collection (while providing effective barriers against humidity) and migration of ions within the PSC structures. 1037,1284,1285 Graphene and its derivatives have also been investigated to form efficient back electrodes (CE) as an alternative to Au or Ag. 1217,1227 Beside reaching relevant Z up to 18.65%, 1230 the use of metal-free back electrodes eliminates the degrading reaction between the perovskite layer and Au and Ag, which are the cause of device instability.…”

Interface Engineering of Inverted Perovskite Solar Cells Using a Self‐doped Perylene Diimide Ionene Terpolymer as a Thickness‐Independent Cathode Interlayer†

“…When 10 wt% Bphen is added into the PNPDIN, 21.28% PCE is achieved, which is one of the best performances of PerSCs based on PDI CILs (Figure 1). [ 18,23‐37 ] More importantly, the high conductivity and good film morphology of PNPDIN also made the mixed CIL good thickness tolerance. The optimal PCE of the inverted PerSC still showed 20.46% for film thicknesses of up to 37 nm.…”

Vacuum‐Processed Perovskite Solar Cells: Materials and Methods

“…Similar to solution-based methods that charge transporting layer affects device performance, [26][27][28] in vacuum-based method, the property of the perovskite such as its grain size and the PSC efficiency are strongly affected by the charge transport layer, which is below the perovskite layer when the perovskite crystal grows in vacuum-based method. Therefore, it is important to select a suitable HTL for the p-i-n structure or a suitable electron transport layer (ETL) for the n-i-p structure.…”