Light decay: When charging the surface of the photosensitive drum, as the charge accumulates on the surface of the photosensitive drum, the potential continues to rise, and finally reaches the "saturation" potential, which is the highest potential. The surface potential will decrease over time. Generally, the working potential is lower than this potential. This process of natural decrease in potential over time is called the "dark decay" process. When the photosensitive drum is scanned and exposed, the dark area (referring to the surface of the photoconductor not irradiated by light) is still in the dark decay process; the bright area (referring to the surface of the photoconductor of the light irradiated part) has a rapid increase in the carrier density in the photoconductor layer. The conductivity rises rapidly, forming a photoconductor voltage, the charge quickly disappears, and the surface potential of the photoconductor also drops rapidly. It is called "light decay", and finally slows down. 

 Light-induced decay effect: also known as the S-W effect. After a-Si:H film is irradiated by strong light or current for a long time, defects will be generated in the film and the performance of the film will decrease, which is called the Steabler-Wronski effect. There are still many controversies about the cause of the S-W effect, and the micro-mechanism of the recession is still inconclusive. It has become a hot topic in the research of amorphous silicon materials at home and abroad. The general view is that the SW effect is caused by the light causing a new dangling bond defect state (deep energy level) in the band gap. This defect state will affect the position of the Fermi level EF of a-Si:H thin film materials. , So as to change the distribution of electrons, which on the one hand causes changes in optical properties, and on the other hand affects the recombination process of electrons. These defect states become extra recombination centers of electrons and holes, which increase the electron trapping cross section and decrease the lifetime.

        In a-Si:H thin film materials, Si-H bonds and Si-Si bonds similar to crystalline silicon can exist stably. These bonds have a large bond energy and are not easily broken. Due to the disorder of the a-Si:H material structure, the bond length and bond angle of some Si-Si bonds change and the Si-Si bonds are in a strained state. The chemical potential of the high strain Si-Si bond is equivalent to that of H, which can be interrupted by external energy to form Si-H bonds or recombine stronger Si-Si bonds. If the broken strained Si-Si bond is not reconstructed, the dangling bond density of the a-Si:H film increases. In order to better understand the mechanism of the SW effect and control the dangling bonds in the a-Si:H film, in order to find stabilization methods and processes, for more than 20 years, scientists at home and abroad have made unremitting efforts and proposed a large number of There are mainly weak bond break (SJT) model, "H glass" model, H collision model, Si-H-Si bridge bond formation model, "defect pool" model, etc., but there is still no unified viewpoint.

        The above is a brief analysis of LED light decay. Taking luminous decay as the criterion for judging product life is another major advancement in the LED display industry!