Rapid and high-resolution patterning of microstructure and composition in organic semiconductors using ‘molecular gates’

Abstract

Photolithography has been a major enabling tool for miniaturisation of silicon devices that underpinned the electronics revolution. Rapid, high-resolution patterning of key material characteristics would, similarly, accelerate the advent of molecular electronics and photonics. Here we advance a versatile approach employing local diffusion of functional small-molecular compounds through a solution-processed 'molecular gate' interlayer. Diffusion is activated using laser light or solvent vapour jets-a process that can be finely modulated down to molecule-on-demand deposition precision with almost photolithographic resolution (<5 μm) and speeds (3 mm s-1). Examples of principal pattern types are presented including molecular conformation for integrated photonics; chain orientation for polarised security features and micro-engineered electronics; and doping with local conductivity values >3 S cm-1 for improved electronic devices. Finally, we demonstrate the unique capability for one-step patterning of multiple functionalities by spatially modulating composition in ternary blends, leading to locally tunable photoluminescence from blue to red.

Gentle Patterning Approaches toward Compatibility with Bio‐Organic Materials and Their Environmental Aspects

“…Several groups have shown successful patterning of bio-organic objects with the help of multiphoton lithography fabricating various 3D scaffolds. [142,167] Perevedentsev et al [169] showed a rather unconventional path towards patterning molecular electronic devices utilizing laser radiation. The authors achieved a photolithographic resolution of less than 5 m.…”

“…LL [142,[167][168][169][170][171] Fibroin [142] No No 75 mW/cm 2 (800 nm femtosecond laser) Ambient 350 200 BU* + TD Home-built writing system * BU in terms of resist composite Molecular gates [171] Chlorobenzene 110 °C baking 5-12 mW/cm 2 (532 nm laser) 1000 TD NIL [172][173][174][175][176] Cellulose derivatives [173] No No Baking 140 °C Ambient 250 250+ BU+TD EBL is required to fabricate the mold.…”

“…Perevedentsev and Campoy‐Quiles [ 171 ] showed a rather unconventional path toward patterning molecular electronic devices utilizing laser radiation. The authors achieved a photolithographic resolution of less than 5 µm.…”

Polarization‐Sensitive Photodetectors Based on Directionally Oriented Organic Bulk‐Heterojunctions

“…Hence, in the present work we employ the so-called "crystallizable" solvents [25,[29][30][31][32] for enabling on-demand directional orientation of organic semiconductors. With foresight to subsequent extension to inkjet-printing fabrication, [31] we devise an entirely solution-based fabrication approach based on airassisted blade-coating for the deposition of oriented donoracceptor blends.…”

Imaging‐Based Metrics Drawn from Visual Perception of Haze and Clarity of Materials. I. Method, Analysis, and Distance‐Dependent Transparency

“…This presents one with difficulties in reconciling haze and clarity into a meaningful measure of transparency that correlates with visual perception. Finally, the typical haze‐meter provides only a single spatially‐averaged value for a ≈5 cm 2 area, which renders it particularly unsuitable for analysis of heterogeneous/patterned samples [ 22,23 ] or accurate identification of local defects in quality control applications. [ 10 ] Reflective of these limitations of the ASTM D1003 is the fact that recent reports on analysis of thin‐film materials have increasingly resorted to alternative, non‐standardized measurements for haze.…”