Highly Transparent, Highly Thermally Stable Nanocellulose/Polymer Hybrid Substrates for Flexible OLED Devices

Abstract

Flexible organic light-emitting diode (OLED) devices based on polymer substrates have attracted worldwide attention. However, the current OLED polymer substrates are limited due to weak thermal stability, which is not compatible with the high temperature in OLED fabrication. Here, we developed a novel nanocellulose/polyarylate (PAR) hybrid polymer substrate with both high transparency and excellent thermal properties. Benefiting from the nanometer scale of the cellulose nanofibrils (CNFs) and the efficient interfacial interaction with PAR, the substrate exhibited greatly improved thermal stability, with a glass transition temperature of 192 °C, the thermal decomposition temperature of 501 °C, and upper operating temperature up to over 220 °C. Meanwhile, the hybrid substrate exhibits outstanding mechanical properties. Notably, no apparent transparency loss was observed after the CNF addition, and the hybrid substrate maintains a high transmittance of 85% and a low haze of 1.75%@600 nm. Moreover, OLED devices fabricated on the hybrid substrates exhibit a much improved optoelectrical performance than that of the devices fabricated on the conventional poly(ethylene terephthalate) (PET) substrates. We anticipate this research will open up a new route for fabricating flexible high-performance OLEDs.

Aqueous Modification of Chitosan with Itaconic Acid to Produce Strong Oxygen Barrier Film

“…Therefore, together with very high transparency, the modified chitosan film could be a similar or even better candidate than CNF films as a supporting layer for electronics, such as flexible solar cell 52 , 53 and organic light-emitting diodes. 54 As stated above, modified chitosan has a yield strength that is in line with that of high-strength CNFs, whereas the visible light transparency of modified chitosan is very high, which in the case of CNFs is generally obtained using hazardous halogenated chemicals. 55 However, before the modified chitosan could be used in electronics, a problem arising from high hygroscopy and poor water tolerance (CNF films exhibit a similar problem 56 ) should be solved.…”

“…The permanent deformation can be adverse in many applications, such as electronics, as it could lead to dysfunction and replacement of the component. Therefore, together with very high transparency, the modified chitosan film could be a similar or even better candidate than CNF films as a supporting layer for electronics, such as flexible solar cell 52,53 and organic light-emitting diodes. 54 As stated above, modified chitosan has a yield strength that is in line with that of high-strength CNFs, whereas the visible light transparency of modified chitosan is very high, which in the case of CNFs is generally obtained using hazardous halogenated chemicals.…”

Recent advances in efficient emissive materials-based OLED applications: a review

“…Glass (rigid and ultra-thin flexible glass), metal foil, and plastic foil are used as substrates. The substrate should have the following properties [77,78]…”

Electron Beam Induced Tailoring of Electrical Characteristics of Organic Semiconductor Films

“…Presently there is massive demand of flexible electronic devices because of its advantageous characteristics including robustness, roll ability, light weight, low cost and cannot be broken under shock [66][67][68][69][70][71][72][73]. The flexibility makes organic film based electronic devices superior over its inorganic counter parts.…”

“…The most important characteristics of conducting polymers, to make it suitable candidate for electronic devices, are low cost [120], flexible [121], solution processable [122][123][124][125][126] and foremost non toxic [127][128][129]. Therefore as far as device applications are concerned, the conducting polymers (CPs) have tremendous role in different fields including sensors [130][131][132][133], solar cells [134,135], batteries [136], organic light emitting diodes (OLED) [69,137,138], electromagnetic shielding [139,140] and thermoelectric power generators [141][142][143][144]. Normally like molecular semiconductors the application of CPs, in various electronic devices, is determined by their electrical properties and in this connection, tailoring of electrical conductivity is the most targeted feature.…”