Tetrabutylammonium Bromide Functionalized Ti₃C₂T_x MXene as Versatile Cathode Buffer Layer for Efficient and Stable Inverted Perovskite Solar Cells

Abstract

2D Ti 3 C 2 T x MXene, possessing facile preparation, high electrical conductivity, flexibility, and solution processability, shows good application potential for enhancing device performance of perovskite solar cells (PVSCs). In this study, tetrabutylammonium bromide functionalized Ti 3 C 2 T x (TBAB-Ti 3 C 2 T x ) is developed as cathode buffer layer (CBL) to regulate the PCBM/Ag cathode interfacial property for the first time. By virtue of the charge transfer from TBAB to Ti 3 C 2 T x demonstrated by electron paramagnetic resonance and density functional theory, the TBAB-Ti 3 C 2 T x CBL with high electrical conductivity exhibits significantly reduced work function of 3.9 eV, which enables optimization of energy level alignment and enhancement of charge extraction. Moreover, the TBAB-Ti 3 C 2 T x CBL can effectively inhibit the migration of iodine ions from perovskite layer to Ag cathode, which synergistically suppresses defect states and reduce charge recombination. Consequently, utilizing MAPbI 3 perovskite without post-treatment, the TBAB-Ti 3 C 2 T x based device exhibits a dramatically improved power conversion efficiency of 21.65% with significantly improved operational stability, which is one of the best efficiencies reported for the devices based on MAPbI 3 /PCBM with different CBLs. These results indicate that TBAB-Ti 3 C 2 T x shall be a promising CBL for high-performance inverted PVSCs and inspire the further applications of quaternary ammonium functionalized MXenes in PVSCs.

A robust and thickness-insensitive hybrid cathode interlayer for high-efficiency and stable inverted organic solar cells

“…The PFOPy CIL shows remarkable PL peaks at 400 and 420 nm, while the PL signals are totally absent for the PFOPy-N CIL, indicating the efficient electron transfer between PFOPy and PDINN. Electron paramagnetic resonance (EPR) was further used to investigate electron transfer characteristics of interfacial materials, 37 and Fig. 3b displays the EPR results of PFOPy, PDINN and PFOPy-N in a solid state.…”

Ti3C2Tx MXene: A New Promising 2D Material for Optoelectronics

“…The latter method has raw materials which are less expensive than Ti 2 AlC and TiC precursors . Ti 3 AlC 2 is generally preferred as the precursor for the synthesis of MXene because it is stable at temperatures required for the synthesis process (1350 °C or higher) . However, a less dense block of the Ti 3 AlC 2 MAX phase is easier to mill into powder without applying pressure.…”

“…Several review articles discussed the material properties of MXenes and their applications, especially in photocatalysis , and energy storage. − The use of MXenes in general for optoelectronic applications was also summarized by Wang et al, Liu et al . and Hantanasirisakul et al Later on, numerous interesting developments were reported. − Figure shows the timeline and major milestones of Ti 3 C 2 T x MXene over the years in the field of optoelectronic applications. Thus, an article solely focusing on the Ti 3 C 2 T x MXene and its optoelectronic applications would be appropriate now for researchers on this topic to stay up to date on the recent developments.…”

Recent advances in electrode interface modifications in perovskite solar cells

“…[66][67][68][69][70] To replace BCP, multiple EIMs such as organic small molecules, polymers, organic-inorganic hybrid compounds, and inorganic metal oxides have been developed and shown enhancement in both the efficiency and the stability for PSCs. [71][72][73][74][75][76][77] Organicinorganic hybrid EIMs with the advantages of both the structure tunability of organic molecules and the stability of inorganic materials have the potential to overcome the instability of the cathode interface. (TOASiW 12 ) (Fig.…”