Materials for single photon sources keep attracting attention owing to the recent development of quantum information technologies such as computing, communications, cryptography, sensing, and metrology. However, commercializing such materials is still facing difficulties for solid reproduction and operations at room temperature because most single photon sources acquire sufficient photon generation efficiencies only at cryogenic temperatures. Here, we review colloidal quantum dots synthesized at low cost and showing high fluorescence efficiencies at room temperature. We discuss the physical and optical characteristics of chemically synthesized colloidal quantum dots, and then relevant single photon measurements and single photon devices.