Surface-Engineered Ti3C2Tx with Tunable Work Functions for Highly Efficient Polymer Solar Cells

Ti3C2Tx, as a newly investigated 2D material, has gained great attention owing to its metallic conductivity, tunable work function (W-F), and unique electrical property. However, its W-F can be further adjusted to meet the needs of optoelectronic devices. Here, surface-engineered Ti3C2Tx is fabricated with tunable W-F by treating with ethanolamine and rhodium chloride (RhCl3). Ethanolamine treated Ti3C2Tx can induce the chemical adsorption of -NH2 on Ti3C2Tx with hydrogen-bonding, which causes the decreased W-F, while chemical doping with RhCl3 leads to the improvement of W-F, which is achieved by the downshift of Femi level of Ti3C2Tx. Moreover, the ethanolamine and RhCl3 can effectively passivate the vacancies of Ti. As such, the surface-engineered Ti3C2Tx is more suitable as buffer layer for polymer solar cells (PSCs) by enhancing the interfacing characteristics of the Ti3C2Tx/active layer. The PSCs with engineered Ti3C2Tx for electron or hole transport layers can exhibit a power conversion efficiency of 15.88% or 15.54%. These efficiencies can be compared with those of devices with a conventional transport layer. This work provides a facile strategy to realize the work function tunability of Ti3C2Tx, and also shows that the tuned Ti3C2Tx has a certain application prospect in photovoltaic devices.

Automated summary

Ti3C2Tx has been surface-engineered with tunable work function (W-F) using ethanolamine and rhodium chloride. The treated Ti3C2Tx exhibits improved interface characteristics and higher efficiency in polymer solar cells.