New concept correlated electron solar cell demonstrated
Competing electronic phases at interface enable higher efficiency solar cells
Graduate School of Engineering / Faculty of Engineering
When a light is illuminated on a charge-ordered insulating state typically observed in transition-metal oxides, it is known that the collective activation of localized charges occurs leading to phase transition from an insulating into a metallic state. During this photoinduced phase transition, multiple charge carriers are generated from one photon. Once this multiple carrier generation is applied to a solar cell, great improvement in photo-electron energy transfer can be expected. This “correlated electron solar cell” has been attracting attention as a potential next-generation solar cell.
The research group of Professor Masashi Kawasaki at the Graduate School of Engineering has investigated the photovoltaic properties under magnetic fields of heterojunctions consisting of a semiconductor and perovskite-type manganites, which are a well-known system showing photoinduced phase transition. The researchers found that the photo-electron conversion efficiency is greatly enhanced by applying magnetic fields when the manganite has an appropriate lattice distortion and chemical composition. This result indicates that a phase competing state is induced at the interface of this junction. In addition, such a junction showing a clear a magneto-photovoltaic effect had a larger short-circuit current compared to other junctions with small magneto-photovoltaic effect. A possible scenario for this photocurrent enhancement is that local photoinduced phase transitions occur near the interface accompanied by multiple carrier generation. This important result are is a significant step towards the development of a correlated electron solar cell.
Z. G. Sheng, M. Nakamura, W. Koshibae, T. Makino, Y. Tokura, and M. Kawasaki,
“Magneto-tunable photocurrent in manganite based heterojunctions”,
Nature Communications Online Edition: 2014/8/1 (Japan time), doi: 10.1038/ncomms5584.
Article link (Publication, UTokyo Repository)