Tandem photovoltaic device and production method

A tandem photovoltaic device, comprising:

• an upper cell unit, a lower cell unit and a tunnel junction located between the upper cell unit and the lower cell unit, and light transmits the upper cell unit onto the lower cell unit when the tandem photovoltaic device works;
• wherein
• the lower cell unit is a crystalline silicon cell;
• the tunnel junction comprises an upper transport layer, a lower transport layer and an intermediate layer located between the upper transport layer and the lower transport layer, wherein the upper transport layer and the lower transport layer are in direct contact with the intermediate layer, respectively, the upper transport layer corresponds to a first conducting type, the lower transport layer corresponds to a second conducting type, and the first conducting type is different from the second conducting type;
• a material of the lower transport layer is selected from one of crystalline silicon, amorphous silicon, nanocrystalline silicon, amorphous silicon carbide, nanocrystalline silicon carbide and crystalline silicon carbide, and the doping concentration of the lower transport layer is 1015 cm−3-1019 cm−3, and the doping concentration of the lower transport layer increases progressively along a direction facing the intermediate layer;
• and
• the intermediate layer is an ordered defect layer, a space scale of defects of the ordered defect layer is 0.5 nm-2 nm, and an average center distance of the defects is 1 nm-100 nm;
• or
• the intermediate layer is a continuous thin layer, wherein when a material of the intermediate layer is a metal, a thickness of the intermediate layer is 0.5 nm-2 nm;
• and when a material of the intermediate layer is a semiconductor material, a doping concentration of the continuous thin layer is 1020 cm−3-1021 cm−3;
• or
• the intermediate layer comprises a first layer contacted with the lower transport layer and a second layer contacted with the upper transport layer, wherein a conducting type of the first layer is same as a conducting type of the lower transport layer, a conducting type of the second layer is same as a conducting type of the upper transport layer, a doping concentration of the first layer is 10 times-10000 times of a doping concentration of the lower transport layer, and the doping concentration of the first layer is less than or equal to 1021 cm−3;
• a doping concentration of the second layer is 10 times-10000 times of a doping concentration of the upper transport layer, and the doping concentration of the second layer is less than or equal to 1021 cm−3.