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Updated: Jul 10, 2026

Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light
Published on: September 12, 2014
Two-step photon up-conversion solar cells
Shigeo Asahi1, Haruyuki Teranishi1, Kazuki Kusaki1
1Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
This study introduces a novel two-step photon up-conversion solar cell (SC) that significantly boosts energy conversion efficiency. By utilizing a unique hetero-interface, it achieves a two-order-of-magnitude increase in photocurrent for improved solar energy harvesting.
Area of Science:
- Materials Science
- Renewable Energy
- Semiconductor Physics
Background:
- Solar cell (SC) efficiency is limited by transmission losses of below-gap photons.
- Photon up-conversion offers a promising route to generate additional photocurrent by utilizing sub-bandgap photons.
Purpose of the Study:
- To develop a two-step photon up-conversion solar cell (SC) to overcome efficiency limitations.
- To enhance photocurrent generation by effectively utilizing below-gap photons.
Main Methods:
- Fabrication of a hetero-interface solar cell using Al0.3Ga0.7As and GaAs with different bandgaps.
- Implementation of a two-step photon up-conversion mechanism involving excitation and electron pumping at the hetero-interface.
- Integration of InAs quantum dots at the hetero-interface to enhance up-conversion efficiency.
Main Results:
- Demonstrated efficient two-step photon up-conversion by utilizing below-gap photons for both materials.
- Observed a significant increase in additional photocurrent, exceeding previous reports by approximately two orders of magnitude.
- Reported an enhancement in photovoltage alongside the increased photocurrent.
Conclusions:
- The developed two-step photon up-conversion SC shows high potential for next-generation high-efficiency solar energy conversion.
- The strategy of using a hetero-interface with strategically chosen materials and quantum dots is effective for boosting SC performance.
- This approach offers a viable pathway to break the theoretical efficiency limits of current solar cell technologies.
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