S.A. Shahahmadi

Amorphous Silicon Single-Junction Thin-Film Solar Cell Exceeding 10% Efficiency by Design Optimization

The conversion efficiency of a solar cell can substantially be increased by improved material properties and associated designs. At first, this study has adopted AMPS-1D (analysis of microelectronic and photonic structures) simulation technique to design and optimize the cell parameters prior to fabrication, where the optimum design parameters can be validated. Solar cells of single junction based on hydrogenated amorphous silicon (a-Si:H) have been analyzed by using AMPS-1D simulator. The investigation has been made based on important model parameters such as thickness, doping concentrations, bandgap, and operating temperature and so forth. The efficiency of single junction a-Si:H can be achieved as high as over 19% after parametric optimization in the simulation, which might seem unrealistic with presently available technologies. Therefore, the numerically designed and optimized a-SiC:H/a-SiC:H-buffer/a-Si:H/a-Si:H solar cells have been fabricated by using PECVD (plasma-enhanced chemical vapor deposition), where the best initial conversion efficiency of 10.02% has been achieved ( V,  mA/cm2 and ) for a small area cell (0.086 cm2). The quantum efficiency (QE) characteristic shows the cell’s better spectral response in the wavelength range of 400 nm–650 nm, which proves it to be a potential candidate as the middle cell in a-Si-based multijunction structures.

Solar Photovoltaic Technologies: From Inception Toward the Most Reliable Energy Resource

The ever-increasing global energy needs due to continual population growth, imminent depletion of fossil fuels, as well as mitigating environmental pollutions around the globe have compelled mankind to search for alternatives in recent years. Among many known alternatives, solar photovoltaic (PV) technology has undoubtedly proven itself worth as one of the mainstream renewable energy resources for its various merits. Solar photovoltaic technology is capable to fit into any requirements with freedom in scalability from milli-watt to almost giga-watt range of demand and response. In years, solar PV technology has shown its inherent potential with versatility in material usage, diversified capability in energy production, as well as sustainability with minimal or almost no adverse environmental effect. This chapter will present the chronological history of the most potential solar PV technologies from the discovery of the science as “photovoltaic PV effect” through the journey of the technological development toward becoming the most reliable energy resource of the near future.

A Comparative Study between Silicon Germanium and Germanium Solar Cells by Numerical Simulation

This paper presents the performance between silicon germanium (SiGe) and crystalline germanium (Ge) solar cells in terms of their simulated open circuit voltage, short circuit current density, fill factor and efficiency. The PC1D solar cell modeling software has been used to simulate and analyze the performance for both solar cells, and the total thickness is limited to 1μm of both SiGe and Ge solar cells. The Si0.1Ge0.9 thickness is varied from 10nm to 100nm to examine the effect of Si0.1Ge0.9 thickness on SiGe solar cell. The result of simulation exhibits the SiGe solar cell give a better performance compared to Ge solar cell. The efficiency of 9.74% (VOC = 0.48V, JSC = 27.86mA/cm2, FF =0.73) is achieved with Si0.1Ge0.9 layer of 0.1μm in thickness whilst 2.73% (VOC = 0.20V, JSC = 27.31mA/cm2, FF =0.50) efficiency is obtained from Ge solar cell.

Effects of germanium layer on silicon/germanium superlattice solar cells

Silicon germanium solar cells have widely been explored in recent years due to the property of germanium material that is capable to absorb light in low energy (IR range). However, the lattice mismatch between the silicon and germanium materials may lead to misfit dislocation defect on the solar cell. The defect can be reduced by arranging the silicon and germanium materials in superlattice (multilayer) structures whereby more lights can be absorbed by the solar cell which will increase its efficiency. In this paper, PC1D solar cell modeling software has been used to simulate and analyze the effects of the germanium thickness on the silicon/germanium superlattice (multilayer) solar cell. The total thickness is limited to 1μm. The simulation result shows that an efficiency of 10.16% (VOC = 0.4521V, ISC = 3.337A, FF =0.6734) is achieved with 0.2μm-Ge and 0.2μm-Si window layer, and 0.6μm-Si absorber layer.