VATIS UPDATE Article

According to a new research carried out by a team led by Kita Takashi and Asahi Shigeo at the Kobe University Graduate School of Engineering, Japan, a new solar cell design could raise the energy conversion efficiency to over 50% by absorbing the spectral components of longer wavelengths that are usually lost during transmission through the cell. The findings have been published in Nature Communications.

In theory, 30% energy-conversion efficiency is the upper limit for traditional single-junction solar cells, as most of the solar energy that strikes the cell passes through without being absorbed, or becomes heat energy instead. Experiments have been taking place around the world to create various solar cell designs that can lift these limitations on conversion efficiency and reduce the loss of energy. The current world record is at 46% percent for a 4-junction solar cell.

If the energy-conversion efficiency of solar cells surpasses 50%, it would have a big impact on the cost of producing electricity. In order to reduce these large energy losses and raise efficiency, the research team used two small photons from the energy transmitted through a single-junction solar cell containing a hetero-interface formed from semiconductors with different bandgaps. Using the photons, they developed a new solar cell structure for generating photocurrents.