Flexible End-Group Triggered Temporal Supramolecular Reordering on Substrate Surfaces and Its Impact on Electron...

Area of Science:

• Materials Science
• Organic Electronics
• Semiconductor Physics

Background:

• Temporal stability of domain microstructure and morphologies is critical for charge transport in organic field effect transistors (OFETs).
• Solution-processed n-type organic semiconductors face stability challenges due to molecular design trade-offs between processability and temporal disorder.
• Flexible end groups enhance solution processability but can compromise device endurance by introducing temporal disorder.

Purpose of the Study:

• To examine the trade-offs between rigid and flexible end groups in n-type molecular semiconductors.
• To investigate the influence of end group flexibility on morphological reordering in active layer films.
• To understand how molecular design impacts temporal stability and device performance in OFETs.

Main Methods:

• Comparative study of n-type molecular semiconductors with flexible (n-Hex2NDI) and rigid (tBCyH2NDI) end groups.
• Analysis of morphological reordering in active layer films using thermal annealing.
• Evaluation of device performance through current-voltage hysteresis measurements.

Main Results:

• Films with flexible side chains (n-Hex2NDI) showed high sensitivity to thermal annealing, altering molecular arrangement and crystallinity.
• Flexible chains in n-Hex2NDI reduced current-voltage hysteresis, indicating enhanced structural order at elevated temperatures.
• Rigid end groups in tBCyH2NDI resulted in minimal temporal disorder, stable optical properties, and negligible hysteresis changes upon annealing.

Conclusions:

• Rigid end groups in n-type molecular semiconductors promote superior temporal stability and device endurance in OFETs.
• Molecular design, specifically end group rigidity, is crucial for mitigating morphological reordering and ensuring long-term reliability.
• Understanding these structure-property relationships is essential for developing high-performance, stable solution-processed organic electronic devices.