Transfer Printed P3HT/PCBM Photoactive Layers: From Material Intermixing to Device Characteristics

Area of Science:

• Organic electronics
• Materials science
• Device fabrication

Background:

• Fabricating complex organic electronic devices with solution-processable materials is challenging due to material intermixing.
• Achieving abrupt interfaces in simple bilayer structures is difficult with conventional methods.

Purpose of the Study:

• To investigate the feasibility of dry transfer printing for creating abrupt bilayer organic photodiodes (OPDs).
• To assess the impact of thermal annealing on bilayer integrity and device performance.

Main Methods:

• Utilized dry transfer printing with a polydimethylsiloxane (PDMS) stamp to deposit poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) films.
• Characterized interfaces using cross-sectional scanning electron microscopy (SEM), UV/vis absorption spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS).
• Evaluated device performance via J-V characteristics and external quantum efficiencies (EQEs) under different annealing conditions.

Main Results:

• Abrupt interfaces were observed in as-transferred films without thermal treatment.
• Significant material intermixing occurred upon annealing above 100 °C.
• Device performance approached that of bulk heterojunction photodiodes after annealing at 140 °C for 5 min.

Conclusions:

• Dry transfer printing is a viable method for fabricating functional organic multilayers with sharp interfaces.
• Thermal annealing conditions critically influence material intermixing and device performance in transfer-printed organic electronics.
• This technique offers a pathway for developing complex organic electronic devices and understanding photoactive layer composition.