Controllable preparation of CdSe@ZnS quantum dots and their applications in high-performance LED digital dynamic color display

Quantum dots are broadly used to prepare light-emitting-diode (LED) devices for color display. However, their surface defects such as suspended bonds result in low photoluminescent (PL) properties. Here, surface coating and polymeric compositing were adopted to fabricate polyvinylidene fluoride (PVDF)/CdSe@ZnS composite films. CdSe quantum dots with various sizes, CdSe@ZnS core-shell quantum dots with narrow size distribution and PVDF-based composite films were prepared. After ZnS coating, PL intensity of quantum dots is enhanced with a blue-shifted emission. Core-shell quantum dots with an increased size emit green, yellow, orange and red light in turn, and their solutions have an increased emission wavelength. Films emit various colors of bright light. Compared to solutions, films have the well-preserved emission wavelengths. Highly dispersed core-shell quantum dots in PVDF are obtained with a preserved fluorescence emission. Fluorescent devices of using the films were constructed on commercial blue-chips. PL emission wavelengths of devices with emitting different colors of light are well-preserved compared to films. White-light-emitting-diode (WLED) device was prepared, and LED lamp emits strong white light. This research can advance a large-scale construction of devices used in LED digital dynamic color display.