Silk Fibroin‐Based Flexible Organic Light‐Emitting Diode with High Light Extraction Efficiency

Abstract

It is an essential issue for the efficiency of flexible organic light‐emitting diodes (OLEDs) to be improved in display and lighting applications. Herein, the use of silk fibroin (SF) as a flexible OLED substrate with enhanced light extraction efficiency (LEE) is reported. Regenerated SF is prepared via a casting method and then coated with conductive indium tin oxide (ITO) via magnetron sputtering. SF‐based flexible OLED outperforms its reference device in terms of turn‐on voltage, peak brightness, and LEE, where glass and polyethylene terephthalate are used as rigid and flexible substrates, respectively. The improved device performance can be ascribed to the low refractive index of SF and its lower surface roughness and more matched energy levels compared to those of other substrates, resulting in a high LEE. Notably, a molecular dipole layer can be formed between the interface of ITO and SF. The dipole moment pointing to the ITO surface effectively changes the ITO work function and reduces the potential barrier height for hole transfer. The work provides new ideas for constructing high‐performance OLEDs on biomass‐based substrates with excellent flexibilities and high LEEs.

Perovskite Light‐Emitting Diodes with an External Quantum Efficiency Exceeding 30%

“…Finite different time domain (FDTD) simulation results (Figure 1f, details in Supporting Information) confirm that the light outcoupling efficiency of the NiO x -based PeLED is only 31.58%, which is far behind that of typical OLEDs (≈40%). [42] According to the light outcoupling efficiency and EQE, the internal quantum efficiency (IQE) of the device was calculated to be 54.08%, which is much smaller than the limit defined by the PLQY (Figure S2f, Supporting Information) of the perovskite films (70.47%). The obvious efficiency gaps between the IQE of the EL devices and the PLQY of the perovskite films are attributed to the nonnegligible electron leakage.…”

Progress and Prospects of Silk Fibroin as an Energy Storage Material

“…[75] Similarly, OLEDs formed by SF coating on conductive ITO via magnetron sputtering showed higher light extraction efficiency (LEE) with turn-on voltage and peak brightness compared to its reference device utilizing glass and polyethylene terephthalate. [74] The mechanical properties of silk substrate were exploited in a work done by Liu et al, [76] where a top emitting organic light emitting device on a silk substrate was demonstrated. The emission of the operating device was steady, free of defects and did not deteriorate even after repeating bending under a very small bending radius.…”

“…The substrate can be bent or conform to different shapes thanks to its mechanical flexibility without losing its structural integrity. [74,75] A sheet resistance of 12 Ω sq À 1 was seen when silver nanowires (AgNWs) were used on SF substrate to create flexible OLEDs, which is comparable to the widely used Polyethylene napthalate (PEN)/ Indium-doped tin oxide (ITO) composite. [75] Similarly, OLEDs formed by SF coating on conductive ITO via magnetron sputtering showed higher light extraction efficiency (LEE) with turn-on voltage and peak brightness compared to its reference device utilizing glass and polyethylene terephthalate.…”

Organic light‐emitting diode behaviors of some synthesized platinum(II)‐based complexes

“…technologies, OLEDs have some advantages because of their economical, flexible, bendable, foldable, transparent, and so on [24][25][26][27][28]. For that reason, it is hoped that OLEDs will take an important place in the display market in the future [29][30][31][32].…”