Crystalline silicon solar battery

Abstract

The invention discloses a crystalline silicon solar battery which comprises a grid metal electrode 22 at the front face, a window layer 23, a second conduction type heavily doped layer 24, a first conduction type lightly doped crystalline silicon substrate 26 and an electrode 27 at the back face in turn. Provided with the second conduction type heavily doped layer 24 which is thin enough and is thick enough in doping density, the invention can lower the recombination loss caused by the window layer 23, provided with the window layer 23, the invention can lower the ohmic loss caused by the second conduction type heavily doped layer 24 which is thin enough and is thick enough in doping density and simultaneously lower the sheltering loss caused by the grid metal electrode 22 at the front face, thereby enabling the transfer efficiency of a usual crystalline silicon solar battery to be enhanced by at least more than 10 percent.

Description

technical field [0001] The invention relates to a solar cell, in particular to a crystalline silicon (single crystal silicon or polycrystalline silicon) solar cell. Background technique [0002] Currently, common crystalline silicon solar cells 10, such as figure 1 As shown, its typical structure includes: front grid metal electrode 12, anti-reflection and passivation layer 13, n + type heavily doped layer 14, p-type lightly doped crystalline silicon substrate 16, and a back electrode 17, wherein the front gate-like metal electrode 12 is directly connected to the n + Type heavily doped layer 14 is connected and forms an ohmic contact; n + Type heavily doped layer 14 is formed on one surface of p-type lightly doped crystalline silicon substrate 16 by methods such as diffusion, ion implantation or epitaxy, and, n + Type heavily doped layer 14 and p-type lightly doped crystalline silicon substrate 16 form a homogeneous p-n junction, and form a p-n junction depletion region (...

AI Technical Summary

Problems solved by technology

Taking the crystalline silicon solar cell with a junction depth of 250nm using the above-mentioned patented technology (hereinafter referred to as the patented cell) as an example, due to the use of a high-conductivity transparent conductive film, when the grid line density is the minimum (0.5 lines / cm), its blocking The loss is about 4.5% lower than that of the usual crystalline silicon solar cells, that is, the patented cell will absorb 4.5% more photons, and the junction depth of 250nm means that the n-type diffusion layer in the patented cell will absorb 10.6% of the photons. A photon can only produce a pair of electron-hole pairs at most, that is, the number of photons directly corresponds to the number of electron-hole pairs, and the recombination loss caused by the front electrode of the transparent conductive film in the patented battery will make almost all of these absorbed Photons become useless, therefore, removing the number of photons absorbed due to reduced shading loss, the patented cell with a junction depth of 250nm will have an additional recombination loss of nearly 6.6%; while at a junction depth of 500nm, the patented cell will have more The recombination loss is as high as 13.7%. Such a high recombination loss will make the conversion efficiency of the patented cell lower than that of a common crystalline silicon solar cell with the same junction depth. This is because, if appropriate anti-reflection and passivation film, such as a silicon nitride film, the n in this usual crystalline silicon solar cell + At least some of the electron-hole pairs generated by the heavily doped layer are not lost

[0014] In summary, if only the high-conductivity transparent conductive film is directly applied to crystalline silicon solar cells, it cannot effectively solve the problems existing in common crystalline silicon solar cells. However, sometimes it will increase the recombination loss, thereby reducing the conversion efficiency of the battery

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