Sensitive Self-Driven Single-Component Organic Photodetector Based on Vapor-Deposited Small Molecules

Area of Science:

• Organic electronics
• Optoelectronics
• Materials science

Background:

• Organic solar cells (OSCs) and photodetectors (OPDs) typically use electron donating and accepting materials.
• This conventional approach faces challenges in scalability and long-term stability.
• High-performance devices often rely on complex bulk heterojunction structures.

Purpose of the Study:

• To develop a high-performance, single-component organic photodetector (OPD).
• To investigate a vacuum-deposited neat oligothiophene derivative (DCV2-5T) as the photoactive layer.
• To demonstrate a novel device architecture for improved manufacturability and stability.

Main Methods:

• Fabrication of a fully vacuum-deposited single-component OPD using DCV2-5T.
• Device optimization to minimize dark current and enhance performance metrics.
• Ultrafast transient absorption spectroscopy to study charge carrier generation dynamics.

Main Results:

• Achieved internal quantum efficiency of 20% at zero bias.
• Demonstrated a very low dark current of 3.4 × 10^-11 A cm^-2 at -0.1 V.
• Obtained specific detectivities of 1 × 10¹³ Jones, fast photoresponse (200 kHz), and a wide linear dynamic range (>150 dB).
• Identified efficient bulk charge generation within <1 ps attributed to strong electronic coupling.

Conclusions:

• Single-component OPDs can achieve performance comparable to state-of-the-art devices.
• The novel device design offers high efficiency, morphological stability, and ease of manufacturing.
• Strong electronic coupling is key to the efficient charge generation mechanism in these devices.