Preparation of Patterned and Multilayer Thin Films for Organic Electronics via Oxygen‐Tolerant SI‐PET‐RAFT

Abstract

An oxygen-tolerant approach is described for preparing surface-tethered polymer films of organic semiconductors directly from electrode substrates using polymer brush photolithography.Aphotoinduced electron transferreversible addition-fragmentation chain transfer (PET-RAFT) approach was used to prepare multiblockp olymer architectures with the structures of multi-layer organic light-emitting diodes (OLEDs), including electron-transport, emissive,a nd hole-transport layers.T he preparation of thermally activated delayed fluorescence (TADF) and thermally assisted fluorescence (TAF) trilayer OLED architectures are described. By using direct photomasking as well as ad igital micromirror device,wealso showthat the surface-initiated (SI)-PET-RAFT approach allows for enhanced control over layer thickness,and spatial resolution in polymer brush patterning at lowc ost.

Luminescent Surface‐Tethered Polymer Brush Materials

“…This photopolymerization technique was also harnessed to prepare patterned films using both photomasking and projection photolithography using a digital micromirror device (DMD). Furthermore, the SI‐PET‐RAFT method was tolerant to oxygen and proceeded with both violet and white LED light sources [13] . This investigation demonstrated that some of the most advanced OLED architectures available today could be prepared using polymer brushes.…”

“…The recent development of several advanced photopatterning techniques has created an opportunity for pixel‐scale patterning of polymer brushes directly from electrode surfaces. Direct growth of semiconducting materials from an electrode surface can reduce many of the defects encountered in traditional solution‐processing methods, such as pinholes [13,97] . As such, polymer brush patterning has the potential to improve the operational stability of optoelectronic devices.…”

“…Direct growth of semiconducting materials from an electrode surface can reduce many of the defects encountered in traditional solution-processing methods, such as pinholes. [13,97] As such, polymer brush patterning has the potential to improve the operational stability of optoelectronic devices. Furthermore, the need for orthogonal solvents to prevent layer intermixing during the preparation of multilayer solution-processed devices is mitigated in this approach, given that polymer brush layers can be grown from the preceding layer and tethered at the opposite end to the substrate.…”

“…The demand for technologies to functionalize and modify surfaces has led to a surge in interest in surface-grafted polymers. Commonly referred to as "polymer brushes", these materials have widely varied properties and have been applied to diverse applications such as anti-fouling coatings, [1][2][3][4][5] energy storage, [6,7] organic electronics, [8][9][10][11][12][13][14][15][16] and chemical sensing. [17][18][19][20][21] Polymer brushes also generally exhibit enhanced thermal and chemical stability over traditional, solution-processed polymer films, making them ideal for use as adhesives, [22][23][24] flame retardants, [25] and to increase solvent interaction with the surface (i. e., wettability).…”

Air‐Tolerant Reversible Complexation Mediated Polymerization (RCMP) Using Aldehyde

“…[30][31][32][33][34] Air-tolerant photocatalyzed RAFT polymerizations were also reported. [35][36][37][38][39][40] Our research group developed an organocatalyzed LRP using an alkyl iodide (R−I) as an initiating dormant species and an organic compound as a catalyst (Scheme 1). Mechanistically, the dormant species (Polymer-I) and the catalyst are supposed to form a halogen bonding complex (Polymer-I•••catalyst), which subsequently reversibly generates the propagating radical (Polymer • ) and an • I•••catalyst complex.…”