Interdigitated CuS/TiO2 Nanotube Bulk Heterojunctions Achieved via Ion Exchange

Abstract

In photovoltaic and optoelectronic applications, a three-dimensional bulk heterojunction is highly desirable in view of the large interfacial area for rapid charge separation. An additional benefit of oriented charge transport is furnished when using anodized titania nanotube arrays as the substrates. However, filling the nanotubes with another p-type semiconductor integrate film, rather than discrete nanoparticles, is difficult with solution-based process. In this study, an interdigitated CuS/TiO2 bulk heterojunction was achieved by filling up TiO2 nanotube arrays with ZnS nanoparticles, and subsequently converting the ZnS nanoparticles into CuS film. Such a combination of pre-filling and post-exchanging process is essential in formation of the interdigitated structure. The rational design of the unique architecture demonstrated in this work provides a facile and general approach to fabricate bulk heterojunctions with other potential semiconductors.