The Investigation of Metal Nanoparticle Plasmonics for Improving the Efficiency of CIGS Solar Cells

This work studies the use of gold (Au) and silver (Ag) nanoparticles in multicrystalline silicon (mc-Si) and copper-indium-gallium-diselenide (CIGS) solar cells. Au and Ag nanoparticles are deposited by spin-coating method, which is a simple and low cost process. The dip in the transmittance yields the plasmonic resonance wavelength and the resonance curves tend to become broader as nanoparticle concentration is reduced. The background transmittance increases as nanoparticle concentration decreases because shadowing effect becomes weaker. The transmittance of Ag nanoparticles is less than that of Au nanoparticles. The resonance wavelengths of Au and Ag nanoparticles at a concentration of 40% are 581nm and 457nm, respectively. The broadening of the resonance wavelength is caused by both the random distribution of nanoparticles and the non-uniform particle of their sizes. This broadening behavior is expected to be favorable for solar cell applications, because it causes light-trapping over a wider range of wavelengths. Larger metal nanoparticles result in stronger scattering effect but also greater metal absorption loss. Different nanoparticle materials have different plasmonic resonance frequencies and yield different light scattering spectra. A low surface coverage by metal nanoparticles yields a weak shadowing effect, but also light scattering effect, and vice versa. The random distribution of nanoparticles by spin coating broadens the resonance wavelength of the transmittance. This broadening favors solar cell applications. Metal shadowing competes with light scattering in a manner that varies with nanoparticle concentration. Experimental results reveal that the mc-Si solar cells that incorporate Au nanoparticles outperform those with Ag nanoparticles. The incorporation of suitable concentration of Au and Ag nanoparticles into mc-Si solar cells increases their efficiency enhancement by 5.6% and 4.8%, respectively. Incorporating Au and Ag nanoparticles into CIGS solar cells improve their efficiency enhancement by 1.2% and 1.4%, respectively. The enhancement of the photocurrent in mc-Si solar cells is lower than that in CIGS solar cells, owing to their different light scattering behaviors and material absorption coefficients.

Project ID:PB10308-4314
External Project ID:MOST103-2221-E182-019