The structural, morphological and optical–electrical characteristic of Cu2XSnS4 (X:Cu,Mg) thin films fabricated by novel ultrasonic co-spray pyrolysis

• A simple and low cost method is introduced to fabricate multi-element films.
• Cu2XSnS4 (X:Cu,Mg) thin films are firstly fabricated by novel ultrasonic co-spray pyrolysis.
• XRD and Raman indicate that Cu2XSnS4 (X:Cu,Mg) have different structures.
• The band gaps of pure Cu2SnS3 and Cu2XSnS4 (X:Cu,Mg) are 1.4, 1.65 and 1.76 eV, respectively.
• CCTS has the lowest resistivity(4.82×10−3 Ω cm) and CMTS has the highest resistivity(1.412×10−1 Ω cm).

In this work,a simple and low cost route is proposed to fabricate pure Cu2SnS3 and Cu2XSnS4 (X:Cu,Mg) thin films.The Cu2XSnS4 (X:Cu,Mg) film was synthesized by a novel dual source ultrasonic co-spray method for the first time.The structural, morphological, optical and electrical properties of the films were well investigated.All the films show different structure,satisfactory morphology and p-type conductivity with a minimum resistivity of 4.82×10−3 Ω cm for Cu2CuSnS4. Optical properties suggest the samples have band gap values of 1.4 eV, 1.65 eV and 1.76 eV for Cu2SnS3,Cu2CuSnS4 and Cu2MgSnS4 respectively, which is the optimal value for high efficient single or tandom thin film solar cell.