Improved Open-Circuit Voltage and Photovoltaic Properties of ZnTeO-Based Intermediate Band Solar Cells With n-Type ZnS Layers

Al-doped ZnS thin films have been grown by molecular beam epitaxy with confirmed n-type conductivity under a wide range of Al cell temperatures between 810 °C and 910 °C at a substrate temperature of 250 °C. An electron concentration up to 4.2 × 1019 cm−3 was achieved with the Al cell temperature of 890 °C. An n-ZnS/i-ZnTe/p-ZnTe solar cell structure was fabricated and under 1 sun illumination this structure showed an improved V OC of 0.77 V, a large short-circuit current density of 6.7 mA/cm2 with a fill factor of 0.60, yielding the power conversion efficiency of 3.1%. The n-type ZnS layer was also applied to the ZnTeO-based intermediate band solar cell structure and results were compared to a similar structure with an n-ZnO layer.