Single-crystalline zinc selenide (ZnSe) nanobelts were fabricated via the ethylenediamine (en)-assisted ternary solution technique and subsequent thermal treatment. Individual ZnSe nanobelts were assembled into nanoscale devices (see figure), showing a high spectral selectivity and photocurrent/immediate-decay ratio and a fast time response, justifying effective utilization of the ZnSe nanobelts as blue/UV-light-sensitive photodetectors.