Five-junction solar cell optimization using Silvaco ATLAS

Multi-junction solar cells have given rise to compact high-efficiency photovoltaic devices, which offer significant improvements over conventional single-junction solar cell designs. This research uses an existing five-junction solar cell design by Fraunhofer ISE to provide the baseline structure for a simulation model based on published cell characteristics. This structure is then optimized by varying doping concentration and material thickness in each active cell layer in order to increase overall photocurrent generation and maximize efficiency. Optimization of solar cell efficiency is carried out via nearly orthogonal balanced design of experiments methodology. Silvaco ATLAS is utilized to simulate the behavior of the multi-junction solar cells’ configurations sampled in the design space. The results of the simulations of points within the sampled design space are loaded into statistical analysis software to construct a stepwise linear regression model to predict the optimum input parameter values to maximize output power and efficiency. The predicted optimum design point is then simulated in the Silvaco ATLAS model. Simulation results are compared to the baseline to analyze improvements such as external quantum efficiency, recombination rate, and current generation. The results following the optimization raised the multi-junction cell output power efficiency from 26.2166% to 37.3682%, while the external quantum efficiencies of the second, third, and fourth junctions were raised 8% to 20%.http://archive.org/details/fivejunctionsola1094556146Lieutenant Commander, United States NavyApproved for public release; distribution is unlimited