Surfactant-like Additives Assisted the Lateral Growth of Pentacene Films

Area of Science:

• Materials Science
• Organic Electronics
• Thin Film Growth

Background:

• Lateral growth of organic thin films is critical for high-performance organic electronic devices.
• Pentacene films are widely used in organic field-effect transistors, but their growth morphology can limit device efficiency.
• Controlling thin film morphology is essential for optimizing charge transport properties.

Purpose of the Study:

• To investigate the effect of rubrene as a surfactant-like additive on the lateral growth of pentacene thin films.
• To understand the molecular mechanisms behind rubrene's influence on pentacene film morphology.
• To correlate enhanced film growth with improved device performance, specifically carrier mobility.

Main Methods:

• Thin film deposition and characterization using Atomic Force Microscopy (AFM) to observe surface morphology.
• Molecular Dynamics (MD) simulations to analyze interlayer diffusion of pentacene molecules.
• Mean Square Displacement (MSD) analysis to quantify molecular diffusion coefficients.

Main Results:

• Rubrene addition significantly enhanced the lateral growth of pentacene films, leading to smoother and larger molecular domains.
• MD simulations revealed that rubrene acts as a surfactant, promoting descending diffusion of pentacene molecules (2.0 × 10^-5 cm² s^-1) over ascending diffusion (1.6 × 10^-5 cm² s^-1).
• Pentacene films grown with rubrene showed a rapid increase in carrier mobility with increasing film thickness due to improved domain connectivity.

Conclusions:

• Rubrene effectively improves pentacene thin film morphology by enhancing lateral growth through surfactant-like action.
• The enhanced molecular diffusion dynamics, particularly descending movement, are key to achieving well-connected domains.
• This strategy offers a novel approach to optimize organic film morphology for developing high-performance organic electronic devices.