Semiconductor and Packaging

IP Approach is pleased to present the exclusive patent for sale “Method of bifacial cell fabrication”, “Bifacial photovoltaic cell”, “Bifacial photovoltaic cell and method of fabrication”, and “Bifacial photovoltaic cell manufacturing process” which includes U.S. Granted Patent US 11,075,316 B2; US 11,387,382 B2; US 11,171,254 B2 and application patent US 20220231183 A1 and their foreign counterparts CN 108352413 B; EP 3365920 B1; ES 2939949 T3; JP 6900370 B2; WO 2017072758 A1; AU 2018399942 B2; CN 111837217 B; EP 3738139 A4; KR 102558939 B1; TWI 791081 B; WO 2019135214 A1; AU 2020284180 A1; CN 114127959 A; EP 3977523 A4; IL 288136 B2; TWI 781407 B and WO 2020240544 A1 assigned to Solaround Ltd. The IP relates to bifacial cell fabrication and, more particularly, but not exclusively, to a method of cell structure formation on a silicon substrate with fine controllable boron doping and suppressed edge shunting. The IP also relates to the field of photovoltaic (PV) cells, particularly to the field of bifacial photovoltaic cells and processes for the manufacturing thereof.

The technology disclosed provides the following  advantages:

• The invention allows simultaneous or sequential diffusion of n-type and p-type dopants at controlled high temperatures (950–1050 °C), streamlining processing steps, reducing thermal cycles, and enhancing manufacturing throughput.
• The invention utilizes a thin boron-containing layer (1–35 nm) and an optional cap layer (e.g., SiO₂, SiN, SiON) to precisely control boron diffusion depth, minimize out-diffusion and cross-doping, protect against environmental degradation, and improve dopant stability during high-temperature processing.
• The invention forms optimized p⁺ layers with tailored sheet resistance (30–150 ohms per square) and surface concentration (<10²⁰ atoms/cm³), resulting in low back surface recombination velocity (<50 cm/s), reduced contact resistance under rear-side electrical contacts, and efficient back-side current collection in bifacial solar cells.
• The invention suppresses edge shunting and cross-diffusion by providing design provisions for boron-free edge zones (0.1–0.5 mm) through selective masking or post-deposition etching, ensuring reliable junction isolation and enhancing device yield without complex isolation steps.
• The invention integrates seamlessly with industrial manufacturing processes such as screen printing, sputtering, texturization, and etching, allowing high-throughput production compatible with existing photovoltaic fabrication workflows.
• The invention supports high-efficiency bifacial solar cells with front-side efficiencies exceeding 19–20.5% and back-to-front current ratios of at least 0.8, maximizing energy yield per unit area and enhancing overall module performance.
• The invention facilitates application of rear-side passivation and antireflective coatings (e.g., SiB, Al₂O₃, SiO₂, SiN, SiON), further reducing surface recombination, improving optical properties, and enabling effective light management.
• The invention maintains compatibility with cost-effective p-type silicon substrates and overcomes traditional boron doping limitations, such as lifetime degradation, through precise, low-dose, and controlled dopant profiling.
• The invention provides a robust and scalable fabrication route for bifacial photovoltaic cells with low sheet resistance in both n⁺ and p⁺ layers, excellent junction isolation, and long-term device stability, while avoiding complex or hazardous high-temperature alloying or gaseous dopant processes.
• The invention supports flexible process integration, enabling multiple sequences of applying n-type and p-type dopants, simultaneous or multistep diffusion, and compatibility with various doping techniques such as sputtering, ion implantation, PVD, and CVD.
• The invention’s cap layer functions include preventing boron out-diffusion and phosphorus cross-diffusion, confining dopants precisely, protecting layers during high-temperature and aggressive processing, enhancing chemical stability, and being easily removable for subsequent steps, thus improving doping uniformity and device reliability.
• The invention improves electrical performance by enhancing bifacial cell parameters, including increased front-side efficiency (≥19%), reduced back surface recombination velocity (<50 cm/s), lower contact resistance, minimized shunting, and formation of stable, high-efficiency junctions.
• The invention enables scalable integration of bifacial cells into modules and energy systems, supporting compatibility with diverse dopant source materials and industrial production lines, promoting broader application across photovoltaic power plants and electrical devices.

Please contact Justin Ehrlickman via email at justin@ipapproach.com or phone at 845-558-7901 to receive a Brokerage Marketing Package.