Micromesh-structured flexible polymer white organic light-emitting diodes using single emissive layer of blended polymer and quantum dots

In this study, poly(N-vinylcarbazole) was blended with CdSe/ZnS core-shell quantum dots of various dimensions to be used as a single emissive layer of flexible polymer white organic light-emitting diodes (WOLEDs). A structure of WOLEDs was deposited on polyethylene terephthalate (PET) substrates. A luminance and maximum luminous efficiency of 4070.2 cd/m2 and 2.84 cd/A were respectively obtained for the WOLEDs prepared using n-type gallium zinc oxide (GZO) and n-type indium gallium zinc oxide (IGZO) films as the electron transport layer and cathode, respectively. Because the current density can be increased by increasing the carrier transport surface area, the 2-μm-periodic SiO2 micromesh was fabricated on PET substrates to enhance the surface area of a MoO3 hole transport layer and a GZO electron transport layer. Furthermore, the GZO electron transport layer could provide a moisture barrier function. Compared with WOLEDs without the SiO2 micromesh, the prepared WOLEDs had an increased current density of 404.5 (compared with 222.8) mA/cm2 when operating at 11 V. Moreover, their associated luminance and maximum luminous efficiency increased to 7016.1 cd/m2 and 3.04 cd/ A, respectively.