High Resolution OLED Using Eco-Friendly Quantum-Dots Functional Color-Filter

Abstract

Recently, the quantum-dots enhancement film (QDEF) has been introduced to improve the color gamut for LCD technology. Although this QDEF has been realized approximately zero cross-talk between the main blue-(B-), green-(G-), and red-(R-) light emissions in LCDs to almost zero, it would have a considerable loss (> 10%) in the intensity of light due to the light absorbed in the resin medium and transparent sheets. To solve this undesirable loss of light, the LCD technology has been adopted the QD-functional CF LCD which is simply adding the B, G, and R-QDs directly to the color filters (CFs) in conventional LCDs using a blue back-light-unit (BLU). Motivated by this idea, we suggest this QDCF technology for organic light emitting diode (OLED) devices. In our research, B-, G-, and R-QD-functional CFs were fabricated by using eco-friendly ZnSe / ZnS and InP-based core/shell structure, showing a high photoluminescence-quantum yield (PL-QY) and a narrow full-width at half-maximum (FWHM) as well as a good flexibility in tuning the suitable PL peak wavelength between emitted from QDs and transmitted from CFs. To make the QD-functional color filter layer, blue, green, and red emitting quantum dots dissolved in hexane of 20wt%. Then they were mixed with the blue, green, and red color filters at a rate of 1 to 1. In order to disperse the QD-functional color filter well, ultra-sonication was performed for 10 minutes. Then, the QD-functional color filter solution was coated on the cleaned substrate using the drop process. After drying for 60 minutes, we analyzed the QD-functional CF structures through photoluminescence and UV-visible spectroscopy. It was confirmed that the B-, G, and R-QDs functional CF OLED exhibited that the PL peak emit at 432, 530, and 621 nm-wavelength with a PL FWHM of 13.4, 39, and 42 nm and a PL-QY of 71, 85, and 75 %, respectively. As a result, the RGB color gamut of the proposed OLED using the fabricated QDs function CFs presented a higher value of 118 % (NTSC) and 88.5% (Rec. 2020) result from the zero cross-talk among PL spectrums of RGB colors (Figure 1). These findings make our study unique and applicable for ultra-super high-resolution OLED and become the cornerstone for trying different types of QDs in QD-functional CFs through a simple, environment-issue free, and cost-effective fabrication process. We will present in detail the wide RGB gamut characteristics and optical properties of QDCF structures using environmentally friendly ZnSe / ZnS and InP quantum dots in addition to driving OLED. Figure 1