A kind of solar cell and preparation method of bandgap graded silicon quantum dot multilayer film

Abstract

A solar battery with a band gap gradual changing silicon quantum dot multilayer film comprises a p type silicon substrate, wherein a thickness gradual changing multilayer amorphous silicon / silicon carbide film structure, a thickness gradual changing amorphous silicon / silicon carbide grease silicon quantum dot / silicon carbide multilayer film structure and a p-i-n battery structure are arranged on the p type silicon substrate, the p-i-n battery structure is formed by the p type silicon substrate, a silicon carbide intrinsic layer (namely an i layer) and the outermost n type nanocrystalline silicon film, and an electrode is guided out on the surface of the p type silicon substrate to form a battery. The thickness of amorphous silicon sub layers in the period of each hydrogenation amorphous silicon / silicon carbide growing towards the surface of the p type silicon substrate is thinned gradually. The amorphous silicon sub layer growing on the p type silicon substrate or close to the p type silicon substrate is the thickest, and the amorphous silicon sub layer growing towards the surface of the p type silicon substrate is the thinnest.

Description

1. Technical field: [0001] The invention belongs to the field of new energy materials and new solar cell devices. In particular, it relates to a solar cell based on a multilayer film structure of silicon quantum dots with a graded band gap and its preparation. 2. Background technology: [0002] Silicon is the material of choice for large-scale application of solar cells, but its band gap is 1.1eV, the near-infrared and near-ultraviolet photon energy in sunlight cannot be fully absorbed and utilized, and the effective response spectrum is only in the range of 500-900nm, so there is a so-called The Shockley-Queisser limit of single-junction silicon solar cell efficiency. In response to this problem, in order to solve the key problem of obtaining high-efficiency Si-based solar cells, the present invention utilizes the preparation of amorphous silicon films / silicon carbide multilayer films with different thicknesses, and through post-processing (thermal annealing or laser annea...

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Problems solved by technology

However, in order to realize this stacked solar cell structure, it is necessary to use silicon nanomaterials of different sizes to form sub-cells, which not only increases the difficulty of the process, but also needs to use heavily doped semiconductor layers to form tunnel junctions between the sub-cells, increasing the battery life. The number of interface layers will cause the recombination loss of carriers on the interface. Another important problem is that the current matching between each sub-cell is difficult to achieve, which greatly limits the efficiency of silicon quantum dot stacked cells.

[0007] Technically speaking, although the nano-Si structure is an important way to realize the effective absorption of short-wavelength light, the current preparation method of nano-silicon materials is generally to form a mosaic-type nano-silicon film from silicon-rich silicon oxide by high-temperature annealing. For the sub-cells composed of nano-silicon, it is necessary to prepare silicon-rich silicon oxide films with different composition ratios to form sub-cells, so that it is difficult for the photo-generated carriers generated in nano-Si to pass through the insulating SiO 2 transported to the electrodes on both sides to form a photocurrent

On the other hand, there are too many interfaces, and the interface states act as recombination centers or traps, which reduces the photogenerated current passing through the junction. Furthermore, the size and distribution of nano-silicon grains are random, which is not conducive to the tunneling operation of the transmission channel, and eventually leads to open circuit voltage. decrease (the measured open circuit voltage is only 463mV) [7], the collection efficiency and conversion efficiency decrease

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