The Technology And Performance Of BZO-TCO Thin Films Deposited By MOCVD And Their Application In Solar Cells

Transparent conductive oxide(TCO) thin films are the key part of the silicon-based solar cells. ZnO:B(BZO) transparent conductive oxide thin films, with good photoelectric performance and high “light-trapping” ability, become research hot issue at present.Therefore, it’s very important to prepare high quality BZO for improving the performance of solar cells.In this paper, BZO thin films with good photoelectric performance were deposited by Metal Organic Chemical Vapor Deposition(MOCVD) technology and used in silicon heterojunction solar cells(SHJ) and p-i-n type single junction amorphous silicon(a-Si:H)thin film solar cells. The main results were as follows:(1) BZO thin films were deposited on glass substrates by MOCVD technology, and effects of doping flow and deposition time on BZO thin film structure, photoelectric properties and morphology were studied. The optimizing preparation technology of BZO thin films with excellent photoelectric properties and “pyramid” surface morphology was obtained.(2) BZO thin films were deposited on the silicon substrates textured by TMAH, and a new-type substrate for SHJ cells was prepared. The experimental results showed that the light reflection of substrates decreased and optical absorption in the near infrared wave band increased because of the addition of BZO films. The new-type substrate, prepared in optimized conditions, was use as the back electrode for SHJ cells, and it’s indicated that light response ability of SHJ cell in the near infrared wave band increased, and the external quantum efficiency(EQE) of solar cell increased by 11% compared to the traditional substrates.(3) Through combining BZO thin film with SiO2 antireflective film, a new-type structure, SiO2 antireflective film/Glass/BZO film, was obtained and then was used as the front electrode in p-i-n type a-Si:H thin film solar cells. The experimental results showed that the SiO2 antireflective film on glass substrate presents amorphous structure, there was agglomerated particle on the surface, the optical refractive index coefficient is 1.28 and the highest optical transmittance is 95.5%. The optical transmittance and the "light trapping" ability of the new-type structure were improved through reducing the light reflection loss ofthe interface at antireflective layer/air by the interference of SiO2 antireflective film.Compared to the traditional front electrode, the new-type front electrode increased the EQE of a-Si:H thin film solar cell by 4%, improved the convection efficiency(η) by 4% also and reached 10.24%.