Generally speaking, in order to more directly improve the photoelectric conversion rate of solar cells and maximize their efficiency in practical applications, battery manufacturers need to use physical means to prepare textured light-trapping structures on the surface of solar cells. Then, in order to scientifically characterize and evaluate the textured light-trapping structure and performance of the solar cell after the preparation process, it must be detected by scientific testing instruments. To this end, Millennial Solar has produced 3D Confocal Microscope, which can efficiently and large-scale measure the grating texture of solar cells with ultra-high measurement accuracy and fully automatic measurement functions, and compare the obtained parameters one by one with industrial standard parameters, so as to make reasonable adjustments and optimizations to the cell!

Light trapping structure and its principle

The light-trapping structure is a surface structure composed of micron or nanoscale protrusions or depressions, which can effectively reduce the reflection of light, increase the scattering and coupling of light, and thereby increase the light absorption rate. Light trapping structures can be applied to different types of solar cells, such as crystalline silicon solar cells, amorphous silicon solar cells, perovskite solar cells, etc.

Light trapping structure diagram

The principle of the light trapping structure is to use phenomena such as refraction, reflection, scattering and interference of light to change the propagation path of light on the surface of the solar cell, increase the residence time of light inside the solar cell, and thereby increase the light absorption rate. Parameters such as the morphology, size, distribution and uniformity of the light-trapping structure will affect the propagation characteristics of light, thereby affecting the degree of improvement in light absorption rate. Generally speaking, the height of the light trapping structure should be greater than the wavelength of light to increase light scattering; the spacing of the light trapping structure should be smaller than the wavelength of light to increase light coupling; the shape of the light trapping structure should be as complex as possible to increase light interference.

How to optimize the design of light-trapping structures?

The design of light-trapping structures is mainly based on numerical simulation or experimental optimization methods to find the optimal morphology, size, distribution, uniformity and other parameters to maximize light absorption and photoelectric conversion rates. Numerical simulation methods can be implemented through finite element method, finite difference time domain method, rigid body sphere approximation method, etc., which can quickly and readily calculate the impact of different structures on light absorption, thus guiding the optimal design of light trapping structures. The method of experimental optimization is to find the best sample by changing the preparation process parameters, preparing different samples, and measuring their light absorption rate and photoelectric conversion rate.

Light trapping structure can also be designed after measurement with sophisticated solar cell testing equipment. The 3D Confocal Microscope produced by Millennial Solar can easily do this. Using the 3D Confocal Microscope for testing, you can objectively and clearly understand the conditions in the detection area. The number of pyramids and the height of a single pyramid, and then comparing the measured data one by one, can achieve a scientifically based design of the light trapping structure.

3D Confocal Microscope

E-mail: market@millennialsolar.com

3D Confocal Microscope is based on the principle of optical technology, combined with precision Z-direction scanning module, 3D modeling algorithm, etc. to conduct non-contact scanning of the device surface and establish a 3D surface image. The number of pyramids is quantitatively detected to provide feedback on the process quality of cleaning, texturing and grid lines.

·Accurate and reliable 3D measurement for real-time confocal microscopy images

·Ultra-high confocal lens, Z-axis display resolution up to 1nm

·Maximum comprehensive magnification of 198-39966 times, accurate measurement of sub-micron morphology

·Fully automatic grid line suede measurement, rapid data generation

The preparation of light-trapping structures on the surface of solar cells can directly improve the photoelectric conversion rate of solar cells through physical methods, thereby helping cell manufacturers to better put the prepared solar cells into practical applications. The 3D Confocal Microscope produced by Millennial Solar can use its ultra-high measurement accuracy to conduct regional measurements on the textured surface of solar cells and compare the various data obtained from the measurements one by one. From this, we can evaluate whether its physical parameters meet industrial production standards!