Ti₃C₂T_x/PEDOT:PSS Composite Interface Enables over 17% Efficiency Non-fullerene Organic Solar Cells

Abstract

Metal carbide Ti 3 C 2 T x as a new two-dimensional material with excellent metallic conductivity, good water solubility, and superior transmittance in the visible light range shows great potential for applications in optoelectronic devices. Herein, Ti 3 C 2 T x /PEDOT:PSS composite films were fabricated by a simple solution process and employed as an anode interfacial layer in organic solar cells. By introducing the Ti 3 C 2 T x /PEDOT:PSS composite interface into the devices, the highest power conversion efficiency (PCE) of 17.26% was achieved while using PM6:Y6 as the active layer, with a high short-circuit current (J sc ) of 26.52 mA/cm 2 and a fill factor of up to 0.76. The PCE is much higher than 15.89% for the pure PEDOT:PSS interfacial layer-based device without doping. The dramatically improved performance was attributed to the increased conductivity of the Ti 3 C 2 T x /PEDOT:PSS composite interface and the increased charge extraction and collection efficiency of the devices. This work presents an effective method to prepare the Ti 3 C 2 T x /PEDOT:PSS composite interface and high-performance organic solar cells.

Recent Advances in Organic and Inorganic Hole and Electron Transport Layers for Organic Solar Cells: Basic Concept and Device Performance

“…This is the first time that MXenes have been reported for optoelectronic devices due to their great transparency in the visible region and excellent conductivity. With the inception of the interest in MXenes, Wang and co-workers investigated that conductivity of the PEDOT:PSS (8.45 S/m) can be significantly improved by the incorporation of the few amount Ti 3 C 3 T x (∼ 9.25–10.41 S/m) shown in Figure a . The PCE of Ti 3 C 2 T x /PEDOT:PSS composite-based devices was significantly increased from 15.89 to 17.26% (active layer PM6:Y6), with a synergistic improvement of J SC and FF due to increased charge extraction and collection efficiency, as compared to the pure PEDOT:PSS based device (Figure b–d).…”

“…(b) Device structures and corresponding (c) J – V characteristics, (d) EQE spectra. Reproduced with permission from ref . Copyright 2021 American Chemical society.…”

“…With the inception of the interest in MXenes, Wang and co-workers investigated that conductivity of the PEDOT:PSS (8.45 S/m) can be significantly improved by the incorporation of the few amount Ti 3 C 3 T x (∼ 9.25− 10.41 S/m) shown in Figure 7a. 163 The PCE of Ti 3 C 2 T x / PEDOT:PSS composite-based devices was significantly increased from 15.89 to 17.26% (active layer PM6:Y6), with a synergistic improvement of J SC and FF due to increased charge extraction and collection efficiency, as compared to the pure PEDOT:PSS based The electrical conductivity of the film was found to be improved by 2% doping of Ti 3 C 2 T x into PEDOT:PSS, with no detrimental influence on the transmittance or surface morphologies of the interfacial layer. The charge transfer between the PEDOT nanocrystals is difficult due to the isolated and unconnected PEDOT nanocrystals, resulting in poor conductivity of PEDOT:PSS.…”

Nonalloy Model-Based Ternary Organic Solar Cells

“…Organic solar cells (OSCs) have attracted much attention in recent years because of their advantages in aspects of light weight, flexibility, semitransparency, low-cost coating methods, and potential in making large-area devices. − Since the report of an A-DA′D-A type nonfullerene acceptor (NFA) named Y6, the power conversion efficiency (PCE) of single-junction OSCs has been boosted to over 18% by optimizing Y6-based devices or developing its derivatives. − In particular, based on the PM6:Y6 blending system a large number of studies have been carried out to improve the device performance, including interface engineering, ternary or quaternary blending, fabrication process improvement, and so on. ,− Among them, the ternary strategy which can extend the absorption spectrum, promote the exciton dissociation, and optimize the film morphology has achieved tremendous success. ,− Notably, most of the ternary systems are constructed based on an alloy-like model (Figure ) in which the third component possessing a similar molecular structure to either a donor or an acceptor can have excellent miscibility with the binary host to form a uniform two-phase mixture, leading to improved OSC performances. ,,− For example, Zhan et al added BTP-M into the PM6:Y6 blend to form the alloy-like model, elevating energy levels of the alloy acceptor and boosting the PCE to 17.03% . Liu et al constructed a high-performance ternary OSC based on a small-bandgap alloy acceptor containing two structurally similar NFAs (Y6 and AQx-3), achieving a PCE of over 18% …”

Two-Dimensional Nanomaterials for Boosting the Performance of Organic Solar Cells

“…The serious electron-hole recombination, low carrier mobility of the active layers, and insufficient sunlight absorption are taking the main responsibility for the limited PCE of the OSCs. Besides, it is well acknowledged that the most commonly used hole transport layer (HTL) material, Poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) exhibits hygroscopicity characteristic, which can easily corrode the indium tin oxide (ITO) electrode material, decreasing the efficiency and stability of the devices [25][26][27][28][29].…”