Two-step photon up-conversion solar cells.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28382945.
- Also identified by DOI 10.1038/ncomms14962 and PMC identifier 5384214.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Reducing the transmission loss for below-gap photons is a straightforward way to break the limit of the energy-conversion efficiency of solar cells (SCs). The up-conversion of below-gap photons is very promising for generating additional photocurrent. Here we propose a two-step photon up-conversion SC with a hetero-interface comprising different bandgaps of Al<sub>0.3</sub>Ga<sub>0.7</sub>As and GaAs. The below-gap photons for Al<sub>0.3</sub>Ga<sub>0.7</sub>As excite GaAs and generate electrons at the hetero-interface. The accumulated electrons at the hetero-interface are pumped upwards into the Al<sub>0.3</sub>Ga<sub>0.7</sub>As barrier by below-gap photons for GaAs. Efficient two-step photon up-conversion is achieved by introducing InAs quantum dots at the hetero-interface. We observe not only a dramatic increase in the additional photocurrent, which exceeds the reported values by approximately two orders of magnitude, but also an increase in the photovoltage. These results suggest that the two-step photon up-conversion SC has a high potential for implementation in the next-generation high-efficiency SCs.