Biowaste‐Derived, Self‐Organized Arrays of High‐Performance 2D Carbon Emitters for Organic Light‐Emitting Diodes

Abstract

Low‐cost flexible organic light‐emitting diodes (OLEDs) with nanoemitter material from waste open up new opportunities for sustainable technology. The common emitter materials generated from waste are carbon dots (CDs). However, these have poor luminescent properties. Further solid‐state emission quenching makes application in display devices challenging. Here, flexible and rigid OLED devices are demonstrated using self‐assembled 2D arrays of CDs derived from waste material, viz., human hair. High‐performance CDs with a quantum yield (QY) of 87%, self‐assembled into 2D arrays, are achieved by improving the crystallinity and decreasing the CDs' size distribution. The CD island array exhibits ultrahigh hole mobility (≈10−1 cm2 V−1 s−1) and significant reduction in solid‐state emission quenching compared to pristine CDs; hence, it is used here as an emitting layer in both indium tin oxide (ITO)‐coated glass and ITO‐coated flexible poly(ethylene terephthalate) (PET) substrate OLED devices, without any hole‐injection layer. The flexible OLED device exhibits a stable, voltage‐independent blue/cyan emission with a record maximum luminescence of 350 cd m−2, whereas the OLED device based on the rigid glass substrate shows a maximum luminescence of 700 cd m−2. This work sets up a platform to develop next‐generation OLED displays using CD emitters derived from the biowaste material.

Potassium Doping to Enhance Green Photoemission of Light‐Emitting Diodes Based on CsPbBr3 Perovskite Nanocrystals

“…The CDs were synthesized according to previous report. [ 41 ] The composite thin films were then allowed to dry at room temperature, before transferring it to a glove box system with low moisture and oxygen (O 2 < 0.1 ppm, H 2 O < 0.1 ppm).…”

Carbon Dots as a Sustainable New Platform for Organic Light Emitting Diode

“…CDs have been used as active layers both dispersed in the matrix to avoid aggregation quenching and as a neat film, leading to increasingly encouraging results mostly when their surface was passivated by a hexadecylamine (HDA) agent [71,79].…”

“…Finally, the LEDs exhibited outstanding stability, which is of great significance for display technology. See Figure 18B-I Singh and colleagues [79] fabricated the first flexible OLED (Figure 19a,b) based on CDs employing self-assembled 2D array of CDs embedded in a PVK emission layer. The flexible device was switched on at 4.3 V and exhibited a blue/cyan emission peaked at about 500 nm (comparable to PL emission, Figure 19c) with LMAX of 350 cd/m 2 and ηc of 0.22 cd/A (Figure 19d,e), whereas the corresponding OLED device based on the rigid glass substrate featured a LMAX of 700 cd/m 2 and ηc of 0.27 cd/A.…”

Carbon Dots as A Sustainable New Platform for Organic Light Emitting Diode

“…As active layers have been used dispersed in the matrix to avoid aggregation quenching, but also as neat film, leading to increasingly encouraging results mostly when their surface was passivated by hexadecylamine (HDA) agent [71,82].…”

“…Finally, the LEDs exhibited outstanding stability (Fig.18e) which is of great significance foe display technology. Singh and colleagues [82] fabricated the first flexible OLED (Fig.19a,b) based on CDs employing self-assembled 2D array of CDs embedded in PVK emission layer. The flexible device switched on at 4.3 V and exhibited a blue/cyan emission peaked at about 500 nm (comparable to PL emission, Fig.19c) with LMAX of 350 cd/m 2 and ηc of 0.22 cd/A ( Fig.19d,e), whereas the corresponding OLED device based on the rigid glass substrate featured a LMAX of 700 cd/m 2 and ηc of 0.27 cd/A.…”