arXiv subjects

Kun-Ta Lin

Publications and source records attributed to Kun-Ta Lin.

2 recordsLinked to original sources

arXiv2024

Forming Long-range Order of Semiconducting Polymers through Liquid-phase Directional Molecular Assemblies

Intermolecular interactions are crucial in determining the morphology of solution-processed semiconducting polymer thin films. However, these random interactions often lead to disordered or short-range ordered structures. Achieving long-range order in these films has been a challenge due to limited control over microscopic interactions in current techniques. Here, we present a molecular-level methodology that leverages spatial matching of intermolecular dynamics among solutes, solvents, and substrates to induce directional molecular assembly in weakly bonded polymers. Within the optimized dynamic scale of 2.5 \r{A} between polymer side chains and self-assembled monolayers (SAMs) on nanogrooved substrates, our approach transforms random aggregates into unidirectional fibers with a remarkable increase in the anisotropic stacking ratio from 1 to 11. The Flory-Huggins-based molecular stacking model accurately predicts the transitioning order on various SAMs, validated by morphologic and spectroscopic observations. The enhanced structural ordering spans over 3 orders of magnitude in length, raising from the smallest 7.3 nm random crystallites to >14 um unidirectional fibers on sub-millimeter areas. Overall, this study provides insights into the control of complex intermolecular interactions and offers enhanced molecular-level controllability in solution-based processes.

cond-mat.soft↗

arXiv2022

Achieving Bright Organic Light Emitting Field Effect Transistors with Sustained Efficiency through Hybrid Contact Design

Organic light emitting field effect transistors (OLEFETs) with bilayer structures have been widely studied due to their potential to integrate high-mobility organic transistors and efficient organic light emitting diodes. However, these devices face a major challenge of imbalance charge transport leading to severe efficiency roll-off at high brightness. Here, we propose a solution to this challenge by introducing a transparent organic/inorganic hybrid contact with specially designed electronic structures. Our design aims to steadily accumulate the electrons injected to the emissive polymer, allowing the light emitting interface to effectively capture more holes even when hole current increases. Our numerical simulations show that the capture efficiency of these steady electrons will dominate charge recombination and lead to a sustained external quantum efficiency of 0.23% over 3 orders of magnitude of brightness (4 to 7700 cd/m2) and current density (1.2 to 2700 mA/cm2) from -4 to -100 V. The same enhancement is retained even after increasing EQE to ~0.51%. The high and tunable brightness with stable efficiency offered by hybrid-contact OLEFETs make them ideal light emitting devices for various applications. These devices have the potential to revolutionize the field of organic electronics by overcoming the fundamental challenge of imbalance charge transport.

physics.app-ph↗