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WSe2 Photovoltaic Device Based on Intramolecular p-n Junction
Yicheng Tang1,2, Zhen Wang2, Peng Wang2,3
1College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, China.
Small (Weinheim an Der Bergstrasse, Germany)
|February 21, 2019
Summary
Researchers developed a high-quality in-plane intramolecular WSe2 p-n junction for photovoltaic devices. This novel approach overcomes limitations of traditional methods, enabling efficient light detection and energy conversion.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Two-dimensional layered materials (2DLMs) offer unique properties like flexibility and tunability for advanced photovoltaic devices.
- Vertical heterojunctions based on 2DLMs are widely studied but suffer from complex fabrication and interface defects.
- There is a need for simpler, high-quality p-n junction fabrication methods in 2DLMs.
Purpose of the Study:
- To realize a high-quality in-plane intramolecular p-n junction using 2D layered materials.
- To investigate the performance of this novel p-n junction as a photovoltaic detector and for microcell applications.
- To overcome the limitations associated with traditional vertical heterojunction fabrication.
Main Methods:
- Fabrication of an in-plane intramolecular WSe2 p-n junction.
- Chemical doping of the n-type region using polyethyleneimine.
- Electrical doping of the p-type region using a back-gate.
- Characterization of the p-n junction quality using an ideality factor.
- Performance evaluation as a photovoltaic detector (responsivity, detectivity, response time).
- Assessment of potential for microcell applications (open-circuit voltage, power conversion efficiency).
Main Results:
- Achieved an ideality factor of 1.66, indicating high-quality p-n junction formation.
- Demonstrated excellent photovoltaic detector performance: responsivity of 80 mA W⁻¹ (≈20% EQE), detectivity > 10¹¹ Jones, and fast response times (200 µs rise, 16 µs fall) at zero bias.
- Obtained a significant open-circuit voltage of 0.38 V and an external power conversion efficiency of ≈1.4%.
Conclusions:
- The in-plane intramolecular WSe2 p-n junction offers a promising alternative to conventional methods.
- This approach yields high-quality junctions with excellent photovoltaic detection capabilities.
- The device shows significant potential for applications in micro-photovoltaic cells and detectors.
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