Surface-Engineered Ti3 C2 Tx with Tunable Work Functions for Highly Efficient Polymer Solar Cells.

Abstract

Ti3 C2 Tx , as a newly investigated 2D material, has gained great attention owing to its metallic conductivity, tunable work function (WF ), and unique electrical property. However, its WF can be further adjusted to meet the needs of optoelectronic devices. Here, surface-engineered Ti3 C2 Tx is fabricated with tunable WF by treating with ethanolamine and rhodium chloride (RhCl3 ). Ethanolamine treated Ti3 C2 Tx can induce the chemical adsorption of NH2 on Ti3 C2 Tx with hydrogen-bonding, which causes the decreased WF , while chemical doping with RhCl3 leads to the improvement of WF , which is achieved by the downshift of Femi level of Ti3 C2 Tx . Moreover, the ethanolamine and RhCl3 can effectively passivate the vacancies of Ti. As such, the surface-engineered Ti3 C2 Tx is more suitable as buffer layer for polymer solar cells (PSCs) by enhancing the interfacing characteristics of the Ti3 C2 Tx /active layer. The PSCs with engineered Ti3 C2 Tx 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 Ti3 C2 Tx , and also shows that the tuned Ti3 C2 Tx has a certain application prospect in photovoltaic devices.