Kesterite photo-absorber by Spatially tuned energy band gap

摘要

The present invention relates to a light absorption layer structure of a solar cell by a spatial energy bandgap modulation method of a custlite Cu2ZnSnSe4 material, and relates to a method of making a conduction band structure having a tilt in a Kestlite light absorption layer. To this end, a light absorbing layer composed of three layers of Cu2Zn (GexSn1-x) Se4 in which Ge is partially substituted for Sn is prepared. If the Ge is substituted for Sn, the energy bandgap of the material is increased. The light absorbing layer is divided into three layers so that the upper and lower layers make more substitution of Ge than the middle part. When the upper layer and the lower layer of the light absorbing layer are compared, the energy band gap is made larger by making more Ge substitution in the lower layer. In the light absorbing layer fabricated with the above structure, photoexcited electrons are collected well toward the transparent electrode located on the upper layer of the light absorbing layer, and a photocurrent increasing effect can be obtained.;