Developed by Chinese researchers, the TOPCon photo voltaic cell is display printed with a paste manufactured from silver and aluminum on the entrance aspect and an aluminum-only paste on the again aspect. They added silicon to the aluminum paste to scale back metallic recombination and enhance the gadget’s open-circuit voltage.
Researchers at Yangzhou University in China have developed a photo voltaic cell based mostly on tunnel oxide passivated contact (TOPCon) expertise by decreasing the usage of costly silver paste with screen-printed aluminum (Al) paste.
“We additional adjusted the method and Al paste to enhance the effectivity,” the corresponding writer of the analysis, Qinqin Wang stated pv journal. “We are testing this innovation along with the Chinese photo voltaic module producer JA Solar.”
The group constructed a 182 mm x 182 mm cell on a 140 μm n-type Czochralski wafer. The rear a part of the passivation contact construction relies on a 1.6 nm silicon monoxide (SiOx) layer and a phosphorus-doped polycrystalline silicon (250 nm) layer, each shaped by low-pressure chemical vapor deposition (LPCVD). The gadget additionally options an aluminum oxide (AlOx) layer made by atomic layer deposition (ALD).
The cell is then display printed with a combination of paste manufactured from silver (Ag) and Al on the entrance aspect and a full Al paste on the again aspect. “The addition of silicon to the Al paste can accommodate the violent response between the Al paste and n + -poly-Si, but additionally decreases the grids conductivity,” the researchers specified. “Thus, Al paste with completely different weight percentages of silicon is utilized in metallization.”
“The addition of silicon to the aluminum paste can stop the response between the aluminum paste and poly-Si, decreasing metallic recombination and bettering the open-circuit voltage,” Wang added, noting that the ohmic contact was established with the formation of Al-Si alloy. “The thickness of the Al-Si alloy decreases with the share of weight of silicon because the Al paste will increase.”
The scientists defined that the photo voltaic cell pattern constructed with the very best proportion of silicon achieved one of the best efficiency. Tested beneath normal lighting circumstances, this gadget achieved an influence conversion effectivity of twenty-two.56%, an open-circuit voltage of 663.6 mV, a short-circuit present density of 40.73 mA/cm2, and a fill issue of 83.48%.
“Although the effectivity is 9.40% decrease than TOPCon cells printed with Ag paste, however the price of Al paste is just 10% of Ag paste;” they defined extra. “In the longer term, the very best effectivity of TOPCon photo voltaic cells printed with Al paste on the again aspect is anticipated to succeed in industrial TOPCon based mostly on Ag paste, making use of laser doping selective emitter expertise (SE) and bifacial poly- Passivation construction.
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