Pseudohalide-Exchanged Quantum Dot Solids Achieve Record Quantum Efficiency in Infrared Photovoltaics
Bin Sun1, Oleksandr Voznyy1, Hairen Tan1
1Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
Advanced Materials (Deerfield Beach, Fla.)
|May 11, 2017
Summary
Pseudohalogens enhance colloidal quantum dot solar cells by reducing defects and enabling thicker films. This breakthrough boosts performance, achieving the highest external quantum efficiency reported for these devices.
Area of Science:
- Materials Science
- Photovoltaics
- Nanotechnology
Background:
- Colloidal quantum dot (CQD) solar cells offer tunable optoelectronic properties.
- Improving CQD solar cell performance requires minimizing trap states and enabling thicker active layers.
- Pseudohalogens present a novel class of materials for surface functionalization.
Purpose of the Study:
- To investigate the application of pseudohalogens for surface passivation in CQD solar cells.
- To enhance charge carrier transport and reduce trap densities in CQD films.
- To achieve higher power conversion efficiencies in CQD-based photovoltaic devices.
Main Methods:
- Utilized pseudohalide thiocyanate anions for hybrid surface passivation of CQDs.
- Employed field-effect transistor studies to quantify trap state densities.
- Fabricated and characterized CQD solar cells with thick active layers.
Main Results:
- Achieved a fourfold reduction in trap state density compared to control samples.
- Enabled the deposition of the thickest CQD active layer reported to date.
- Reached a record external quantum efficiency of 80% at the excitonic peak.
Conclusions:
- Pseudohalogen surface passivation effectively reduces trap states in CQD films.
- Enhanced transport lengths facilitate the use of thicker CQD layers, improving device performance.
- This approach represents a significant advancement in CQD solar cell technology.
