In a brand-new paper released in nature interactions, the Chinese solar producer described that the heterojunction back contact cell it revealed in late 2023 accomplished among the greatest open-circuit voltage ever reported for this cell innovation, along with smaller sized than normal short-circuit existing losses. The outcomes were validated by Germany’s Institute for Solar Energy Research (ISFH).
October 18, 2024 Emiliano Bellini
A group of researchers from Chinese solar module maker Longi has actually explained in a brand-new clinical paper the 27.09%-effective heterojunction back contact (HBC) solar battery it revealed in December 2023.
At the time, Longi just stated the outcome was made it possible for through a brand-new laser visual procedure that costs less than traditional high-cost photolithography procedures, without offering more information. In the brand-new paper, the business discussed that the laser pattern method was established by Longi itself. It not just supplied a comprehensive technical description of the cell architecture, however likewise provided a method on how to enhance contact resistivity, series resistance, and the style of the rear-side pattern.
The group defined that HBC solar batteries have concerns with provider recombination losses and stated these occur from the hole-selective contact area and polarity borders. “We propose options to these problems and develop a clear relationship in between contact resistivity, series resistance, and the style of the rear-side pattern,” they included.
The research study group constructed the 243.0 cm2 cell with a 200 µm-thick Longi M6 274.3 cm2 Czochralski wafer based upon n-type monocrystalline silicon. The front side functions anti-reflection coverings (ARC), and the rear side is divided into 4 areas, which are hole-selective contact (HSC), space area, electron-selective contact (ESC), and HSC plus space.
“We made use of amorphous silicon as passivating contact layers and laser ablation as a mass-production innovation for making HBC solar batteries,” the academics discussed. “This enhances benefits consisting of low leak at the location near the n-p polarity limit, low expense, low deposition trouble, and high harmony.”
Through laser pattern, the scientists used a pulsed green picosecond laser to ablate the overlying i-a-Si: H/p-a-Si: H stack in the created ESC area. The transparent performing oxide (TCO) layer was transferred utilizing the magnetron sputtering strategy.
They likewise utilized pulsed ultra-violet picosecond laser to ablate the created space area to get rid of TCO/p-a-Si: H/i-a-Si: H stack for seclusion, which they stated prevents leak channels. The silicon nitride (SiNx) layer was utilized to avoid the passivation efficiency of the i-a-Si: H/n-a-Si: H stack from being harmed.
Checked under basic lighting conditions, the gadget accomplished a power conversion performance of 27.07% and an open-circuit voltage of 751 mV, with the outcomes being verified by Germany’s Institute for Solar Energy Research (ISFH). The open-circuit voltage worth is shown by Longi as one of the greatest ever taped at the research study level for this sort of solar battery.
Their analysis likewise revealed that the cell, like other HBC gadgets, experiences electrical shading impacts, as providers for both polarities are gathered on the exact same side,