Simulation,optimization And Preparation Of Triple Junction Solar Cells

III-V compound semiconductor solar cells have several advantages,such as high light absorption coefficient,strong radiation resistance,high temperature resistant,high stability,long lifetime,and high photoelectric conversion efficiency,which can be widely used in the field of territorial and space application,thus attract widespread attention from all over the world.GaInP/GaAs/Ge triple junction solar cells is the basis of multi-junction solar cells research,many of the state-of-the-art multijunction soalr cells are the deformation and optimization of GaInP/GaAs/Ge structure.This paper mainly studies the structure design,simulation and optimization,and performance characterization of triple junction solar cell,and the main research contents and results are as follows:1.Selection of simulation models.Firstly,determination of basic models like carrier mobility model and recombination model.Secondly,study and comparation of the commonly used tunnel junction models,and select equivalent resistance model as the tunnel junction model in subsequent simulations.2.Design and optimization of GaInP/GaAs/Ge triple junction solar cells.The solar cells'simulation and optimization are carried out by using Silvaco Atlas.Firstly,three subcells,GaInP,GaAs and Ge are simulated and optimized,respectively.Secondly,influence of layer's thickness and doping concentration,carrier mobility and lifetime on the performance of the solar cells are studied.Thirdly,design and optimization of GaInP/GaAs/Ge triple junction solar cells.By adjusting the thickness of GaInP and optimization of tunnel junction,the short circuit current of GaInP and GaAs subcells become almost equal.The optimized short circuit current is 18.114mA/cm~2,open circuit voltage is 2.637V,fill factor is 89.329%,and photoelectric conversion is 30.919%.3.Preparation and testing of the single junction pn-type GaAs solar cells.Four groups of single junction pn-type GaAs solar cells with different gate widths,spacies between adjacent gate and shading area are prepared by using molecular beam epitaxy(MBE)to study the current-voltage(I-V)characteristic of solar cells and the impact of electrode design on the performance of solar cells.It can be concluded by comparing and analysing the testing results that we must give full consideration to the shading area,contact resistance and current transport capacity in electrode design.The best efficiency of the GaAs sample is 22.14%,which is lower than the simulated result of 24.925%and the world record efficiency of 28.3%.The reasons to cause this difference may come from the difference of cells structure,process conditions and testing facilities.4.Preparation and testing of the GaInP/GaAs/Ge triple junction solar cells.GaInP/GaAs/Ge triple junction solar cells are prepared by using Metal oxide chemical vapor phase deposition(MOCVD).I-V characteristic and external quantum efficiency(EQE)of the solar cells without and with concentration are tested,respectively.The best cell's efficiency without and with concentration is 31.83%and 38.66%.