Effect of incidence angle on fluorescence properties of colloidal infrared quantum dots thin film

The excellent optical properties of colloidal infrared quantum dots make their fluorescence characteristics have a wide application prospect. In practical applications, the colloidal infrared quantum dots usually need to be packaged into the form of thin film to maintain the stable fluorescence characteristics. However, the change of the dispersed form of quantum dots may lead to reduction of the fluorescence efficiency and change of the fluorescence angle characteristics. Thus, the detection system for infrared quantum dots fluorescence intensity was established to study the fluorescence distribution of colloidal infrared quantum dots thin film under excitation light incident in different angles. The experimental results show that when the angle between the excitation light and the sample surface is within a large range of 10°~170°, the fluorescence emergence with fluorescence peak intensity of 70%~80% can be detected in both reflected and transmitted fluorescence regions. The intensity difference between reflected fluorescence and transmitted fluorescence in this range, as well as the change law of fluorescence intensity varies with the excitation light incident angle are related to the concentration and distribution form of quantum dots in the samples, respectively. In addition, with the enhancement of the incident laser energy, the flat range of the sample emergence fluorescence intensity to the change of incident angle is further expanded.