Boosting the Performance of Visible/Near-Infrared Organic Photodetectors via Hole Interface Engineering
Yijing Fan1, Junquan Luo1, Lan Liu1
1Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Guangdong Provincial Engineering Technology Research Center of Vacuum Coating Technologies and New Energy Materials, College of Physics and Optical Engineering, Siyuan Laboratory, Department of Physics, Jinan University, Guangzhou 510632, China.
A novel self-assembled monolayer, (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), optimizes the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) interface in photodetectors. This enhances performance by reducing dark current and improving key metrics for visible/near-infrared detection.
Area of Science:
- Organic electronics
- Materials science
- Device physics
Background:
- Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is a common hole transport layer (HTL) in organic photodetectors.
- PSS accumulation at the PEDOT:PSS interface increases contact resistance and hinders hole injection, limiting device performance.
Purpose of the Study:
- To optimize the PEDOT:PSS interface using a self-assembled monolayer (SAM).
- To improve the performance of visible/near-infrared photodetectors by enhancing charge transfer and reducing losses.
Main Methods:
- Fabrication of a double hole layer photodetector utilizing a (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) SAM to modify the PEDOT:PSS HTL.
- Characterization of device performance, including dark current, switching ratio, responsivity, specific detectivity, response speed, cutoff frequency, and linear dynamic range.
Main Results:
- The 2PACz-modified device exhibited a significantly lower dark current ((1.4 ± 0.6) × 10-5 A at -1 V) and a high switching ratio (7.62 × 105 at 0 V).
- Peak responsivity of 0.31 A/W and specific detectivity of 3.23 × 1012 Jones at 780 nm were achieved.
- Response speed, cutoff frequency, and linear dynamic range were enhanced by 400%, 213%, and 81%, respectively, compared to a reference device.
Conclusions:
- The 2PACz SAM effectively optimizes the PEDOT:PSS interface, reducing recombination losses and improving energy level alignment.
- The developed double hole layer photodetector demonstrates superior performance characteristics, making it suitable for practical visible/near-infrared detection applications.
- This approach offers a novel strategy for fabricating high-performance organic photodetectors.
