Since the performance or output power stability of amorphous silicon solar cells is often affected by various factors in practical application, solar cell manufacturers often try their best to improve the stability of amorphous silicon solar cell performance.

Stability of amorphous silicon solar cell performance

The stability of an amorphous silicon solar cell refers to the degree to which the conversion efficiency changes over time, which is generally measured by the decay rate. The stability of amorphous silicon solar cells is affected by a variety of factors, such as the quality of materials, the design of structure, the control of the preparation process, and environmental conditions. Improving the stability of amorphous silicon solar cells is an important way to improve their performance and reduce their costs.

Methods for improving the stability of amorphous silicon solar cells

Since the performance of amorphous silicon solar cells will deteriorate with time and light in actual use, it will affect their long-term reliability. Therefore, improving the stability of amorphous silicon solar cell performance has become a very important part of the production process of solar cells.

Laminated or heterogeneous structure design

Since amorphous silicon itself is a direct bandgap semiconductor with a high optical absorption coefficient, the photosensitive layer of amorphous silicon solar cells can be made very thin, which can reduce the recombination loss of carriers during transmission and improve efficiency. However, there are also some problems with single-layer amorphous silicon solar cells, such as poor spectral matching, insufficient built-in electric field, and serious interface recombination.

In order to solve these problems, tandem or heterostructure design can be adopted, that is, on the basis of single-layer amorphous silicon solar cells, other materials or structures can be added as photosensitive layers or buffer layers to achieve better utilization of the solar spectrum, enhance the built-in electric field, and reduce interfacial recombination.

Optimized electrode and interface material selection

The choice of electrode and interface materials for amorphous silicon solar cells will also affect their performance stability. On the one hand, the electrode material is required to have good conductivity and light transmission to ensure efficient collection of carriers and transmission of incident light as much as possible. On the other hand, electrode materials are required to have good stability and compatibility to avoid chemical reactions or physical damage with amorphous silicon films, resulting in interface deterioration or delamination. Therefore, optimizing and selecting electrode and interface materials for amorphous silicon solar cells to achieve high-efficiency, stable and low-cost amorphous silicon solar cells is an important method to improve the performance stability of amorphous silicon solar cells.

Surface passivation and encapsulation materials

The surface and interface of amorphous silicon solar cells are the key parts that affect their performance stability, because defect states, impurities, oxides, etc. are easy to be generated here, resulting in increased carrier recombination and reduced efficiency. To reduce the effects of these adverse factors, surface passivation and encapsulation techniques can be employed to improve the stability of amorphous silicon solar cells. Surface passivation technology is to add one or more passivation layers to the surface or interface of amorphous silicon thin films to inhibit carrier recombination and impurity diffusion. The material selection of the passivation layer requires good light transmission, electrical conductivity, stability and compatibility.

Encapsulation technology is to add one or more layers of protective layer to the outside of amorphous silicon solar cells to prevent damage to the solar cell caused by environmental factors such as moisture, oxygen, dust, etc. The material selection of the encapsulation layer requires good light transmittance, waterproofness, oxygen resistance, weather resistance, etc.

The preparation process of amorphous silicon thin film has an important impact on the stability of solar cell performance, and different process parameters will lead to different defect densities, hydrogen content, microcrystalline phase content and other factors, which in turn affect the stability of the solar cell. Generally speaking, increasing the deposition rate, deposition temperature, hydrogen flux, etc. can reduce the defect state density, and increasing the hydrogen dilution ratio can increase the microcrystalline phase content, thereby improving the stability of the solar cell.