The structure and band gap design of high Si doping level Ag1−xGa1−xSixSe2 (x=1/2)

•Study of Ag1−xGa1−xSixSe2 with high Si doping level (x=1/2).•Successful synthesis of new compound named AgGaSiSe4.•AgGaSiSe4 crystallizes in space group Aea2 and adopts a three-dimensional framework.•The energy band gap of AgGaSiSe4 is enlarged compared with Ag3Ga3SiSe8.

Ag1−xGa1−xSixSe2 solutions with high Si doping level (x=1/2) are considered and new compound AgGaSiSe4 has been synthesized. It crystallizes in space group Aea2 and possesses very long axis of a=63.06(1)Å. The three-dimensional framework in AgGaSiSe4 is composed of AgSe3 trigonal planar units, AgSe4 tetrahedra and MSe4(M=Si, Ga) tetrahedra. AgGaSiSe4 is a congruently melting compound with the melt temperature of 759 °C. The diffuse reflectance measurements reveal the band gap of 2.63 eV in AgGaSiSe4 and the value is 0.33 eV larger than that of Ag3Ga3SiSe8 (2.30 eV).

Graphical abstractThe Ag1−xGa1−xSixSe2 with high Si doping level (x=1/2) has been studied and the new compound AgGaSiSe4 was synthesized for the first time. AgGaSiSe4 crystallizes in a new structure type in space group Aea2 and adopts a three-dimensional framework consisting of AgSe3 trigonal planar units, AgSe4 tetrahedra and MSe4 (M=Si, Ge) tetrahedra.Figure optionsDownload full-size imageDownload as PowerPoint slide