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

Abstract

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/m 2 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 SiO 2 micromesh was fabricated on PET substrates to enhance the surface area of a MoO 3 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 SiO 2 micromesh, the prepared WOLEDs had an increased current density of 404.5 (compared with 222.8) mA/cm 2 when operating at 11 V. Moreover, their associated luminance and maximum luminous efficiency increased to 7016.1 cd/m 2 and 3.04 cd/A, respectively. The flexible polymer white organic light-emitting diode (WOLED) with single emissive layer constructed by blending PVK with various dimensional CdSe/ZnS core-shell quantum dots were fabricated and investigated. The 2-μm-periodic SiO 2 micromesh was inserted into the bottom side of the IGZO cathode electrode of the WOLEDs to increase the carrier injection surface area and decrease the carrier propagation length. The luminance and the maximum luminous efficiency of the resulting WOLEDs with SiO 2 micromesh were improved from 4070.2 cd/m 2 and 2.84 cd/A to 7016.1 cd/m 2 and 3.04 cd/A, respectively, in comparison with the WOLEDs without SiO 2 micromesh. • The flexible polymer white organic light-emitting diodes (WOLEDs) was fabricated. • Single emissive layer of blended PVK with quantum dots. • Performance of WOLEDs was improved using 2-μm-periodic SiO 2 micromesh. • Luminance of WOLEDs with SiO 2 micromesh was improved from 4070.2 to 7016.1 cd/m 2 . • Luminous efficiency of WOLEDs with SiO 2 micromesh was improved to 3.04 cd/A.