Surface-Engineered Ti C T with Tunable Work Functions for Highly Efficient Polymer Solar Cells.

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