Triple junction solar cell and preparation method thereof

Abstract

The invention provides a triple junction solar cell and a preparation method of the triple junction solar cell to achieve a reasonable band gap combination of a multi-junction solar cell and to reduce current mismatch without increase in cell manufacturing cost and difficulty. The triple junction solar cell comprises a GaAs substrate, an AlGaInAs transition layer, an InGaAs bottom cell, a first tunnel junction, an InGaAsP middle cell, a second tunnel junction, an InAlAs top cell and an ohmic contact layer, wherein the AlGaInAs transition layer, the InGaAs bottom cell, the first tunnel junction, the InGaAsP middle cell, the second tunnel junction, the InAlAs top cell and the ohmic contact layer are arranged on the GaAs substrate in sequence. Lattice constants among all subsidiary cells are matched, and the band gap combination is 1.93 eV, 1.39 eV, and 0.94 eV. The preparation method of the triple junction solar cell includes the following steps: (1) providing the GaAs substrate; (2) growing the AlGaInAs transition layer, the InGaAs bottom cell, the first tunnel junction, the InGaAsP middle cell, the second tunnel junction, the InAlAs top cell and the ohmic contact layer on the GaAs substrate in sequence; and (3) preparing an upper electrode and a lower electrode on the ohmic contact layer and the GaAs substrate respectively, and obtaining the target solar cell.

Description

Technical field [0001] The present invention relates to the field of solar cells, in particular to a lattice-matched InAlAs / InGaAsP / InGaAs triple-junction solar cell based on a GaAs substrate using a lattice abnormal change buffer layer and a preparation method thereof. Full use of the spectrum, with a theoretical conversion efficiency higher than 51% under concentrating light. Background technique [0002] In the field of III-V solar cells, multi-junction systems are usually used to achieve segmented absorption and utilization of the solar spectrum to obtain higher conversion efficiency. At present, the most researched and more mature systems are GaInP / GaAs / Ge and GaInP / GaAs / InGaAs (~1.0 eV) triple junction batteries. The former currently achieves a maximum conversion efficiency of 32-33% under one sun. However, the main problem of this system is that the Ge battery covers a wide spectrum, and its short-circuit current can reach up to twice that of the other two-junction batte...

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Problems solved by technology

However, there is still a major problem in this system that the Ge battery covers a wider spectrum, and its short-circuit current can reach twice that of the other two-junction batteries. Due to the constraints of the three-junction batteries connected in series, the energy of the solar spectrum corresponding to the Ge battery is not captured. full conversion

However, GaInP / GaAs / InGaAs (~1.0 eV) triple-junction cells often use an inverted growth method due to a 2.1% lattice mismatch between GaAs and InGaAs cells, and then use techniques such as substrate lift-off to increase the growth rate. and the difficulty and cost of the process

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