Photolithography based on nanocrystals

Colloidal chemistry allows the fabrication of metal, semiconductor, oxide, and magnetic nanocrystals (NCs) with well-controlled sizes and shapes, as well as of heterostructures with exotic shapes and composition (1). Such NCs are promising materials in several technological fields. For example, the high-purity emission color of semiconductor NCs has been applied in optical displays (2), and their broadband absorption has been exploited in innovative solar cells (3). Other applications include field-effect transistors, light-emitting diodes, and sensors (4). However, for the fabrication of advanced electronic devices in a parallel and scalable fashion for industrial production, NCs must be integrated into structures to bridge the gap between the nano- and mesoscopic regimes (5). Thus, the organization of NCs in morphologically controlled patterns and processable systems is of paramount importance. On page 385 of this issue, Wang et al. (6) present a pioneering and straightforward approach for the patterning of functional inorganic NCs on substrates with optical lithography. This advance could add--literally--a multilayer dimension to the development of NC-based devices.