Efficient Ti3C2Tx MXene/TiO2 Hybrid Photoanodes for Dye-Sensitized Solar Cells

Abstract

Dye-sensitized solar cells (DSSCs) remain a promising technology for clean energy conversion due to their low cost, simple manufacturing, and high scalability. However, to keep these devices competitive against other photovoltaics like organic (OSCs) and perovskite solar cells (PSCs), it is necessary to enhance their efficiency. These improvements can be achieved by optimizing the charge transport and non-radiative carrier recombination within the operating device. Here, we show the design, fabrication, and subsequent characterization of Ti3C2Tx MXene/TiO2 nanocomposite hybrid photoanodes, supported by computational modeling. Ti3C2Tx MXene/TiO2 hybrid photoanodes containing 0.050, 0.075, and 0.100 wt % two-dimensional (2D) Ti3C2Tx flakes were prepared and investigated. The power conversion efficiency (PCE) of the device is found to be enhanced by 20% when only 0.075 wt % Ti3C2Tx was added to TiO2 due to the increase of electron transport in the photoanode. The density functional theory (DFT) calculations of the MXene–TiO2 interface indicate that the anatase potential is lowered, thus increasing the energy difference between the conduction bands of the N719 dye and the nanocomposite and favoring the migration of electrons toward the output terminal. Moreover, DFT results suggest a better separation of the photocarriers at the nanocomposite–N719 interface, which is supported by the measurement of longer electron lifetimes in the photoanode. These features demonstrate that the introduction of Ti3C2Tx into the photoanode is relevant to promote the energy-to-current conversion of DSCCs. Future approaches shall focus on the implementation of different 2D MXene structures to further improve the performance of these class of materials for direct applications in photovoltaic devices and photochemistry.