Impact of boron doping on electrical performance and efficiency of n-TOPCon solar cell

Wang, Qinqin; Wu, Wangping; Liu, Yunpeng; Yuan, Ling; Yang, Sanchuan; Sun, Yuhan; Yang, Shaojun; Zhang, Qiang; Cao, Yujia; Qu, Hui; Yuan, Ningyi; Ding, Jianning

doi:10.1016/j.solener.2021.08.075

Cited by 21 publications

(5 citation statements)

References 48 publications

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“…The PID‐p susceptibility of the front face of the TOPCon module is attributable in part to the use of boron emitters with sheet resistivity around 180 Ω/◻ 23 and the low solubility of B in Si, which leads to relatively low peak concentration (1 × 10 19 cm −3 range) of B in the p + emitter 24 . An emitter with low p + concentration produces a weaker surface field, reducing the repulsion of minority carrier electrons from the front interface with the dielectric.…”

Section: Resultsmentioning

confidence: 99%

“…The PID-p susceptibility of the front face of the TOPCon module is attributable in part to the use of boron emitters with sheet resistivity around 180 Ω/◻ 23 and the low solubility of B in Si, which leads to relatively low peak concentration (1 Â 10 19 cm À3 range) of B in the p + emitter. 24 An emitter with low p + concentration produces a weaker surface field, reducing the repulsion of minority carrier electrons from the front interface with the dielectric. Then, under negative system voltage, more front surface recombination results from positive charge migrating through the front-side encapsulation toward the dielectric that can further attract minority carrier electrons from the underlying p + emitter.…”

Section: Pid-p Stress and Recovery Test Under Dark Conditionsmentioning

confidence: 99%

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Field‐representative evaluation of PID‐polarization in TOPCon PV modules by accelerated stress testing

Hacke,

Spataru,

Habersberger

et al. 2024

Progress in Photovoltaics

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Potential‐induced degradation‐polarization (PID‐p) can reduce module power, but how to project the extent to which PID‐p may occur in field conditions considering the factors of system voltage, condensed moisture, temperature, and illumination has not been clarified. Using tunnel oxide passivated contact (TOPCon) modules, this work demonstrates a method to test full‐size crystalline silicon PV modules for PID‐p to provide field‐representative results. In initial screening tests with positive or negative 1000 V electrical bias applied at 60°C for 96 h using Al foil electrodes on the glass surfaces, the module type exhibited reversible PID‐p only on the front face when the cell circuit was in negative voltage potential. No PID was detected on the rear after testing in either polarity. We then evaluated the PID‐p sensitivity on the front side under different UV irradiances while maintaining the glass surface wet to estimate real‐world susceptibility to PID‐p. The magnitude of the observed behavior was fit using a previously developed charge transfer and depletion by light model. Whereas power loss with −1000 V applied to the cell circuit at 60°C for 96 h in the dark was about 30%, testing the module front under 0.051 W·m−2 nm−1 at 340 nm UVA irradiation using fluorescent tubes, the mean degradation was only 3%. When the modules were tested in the dark for PID‐p with in situ dark current–voltage (I‐V) characterization, the thermal activation energy for degradation was 0.71 eV; for recovery in the dark, it was 0.58 eV. Whereas recovery from the degraded state at 60°C in the dark without voltage bias was 5% absolute in 38 h, rapid recovery of about 5% absolute was observed with 1000 W·s/m2 exposure at 25°C using a flash tester.

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Section: Resultsmentioning

confidence: 99%

Section: Pid-p Stress and Recovery Test Under Dark Conditionsmentioning

confidence: 99%

Field‐representative evaluation of PID‐polarization in TOPCon PV modules by accelerated stress testing

Hacke,

Spataru,

Habersberger

et al. 2024

Progress in Photovoltaics

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“…J 0,measured plots of n + -poly-Si layers of various thicknesses with different metallization fractions are depicted in Figure 4 . The values of J 0, metal are determined through a straightforward linear interpolation of the measured data points [ 42 , 43 , 44 ]. The results indicate that the n + -poly-Si layers with a thickness of 100 nm have the lowest J 0,measured values, approximately 26 fA/cm 2 .…”

Section: Resultsmentioning

confidence: 99%

“…Wafers with different P-doped poly-Si film thicknesses using two-sided passivation of the SiN x layer were used as J 0 samples. Similar samples with polished surfaces were screen-printed with Ag paste lines on one side only and nine different pitches were used as J 0, metal samples; these which were placed with the fingers facing up and then sintered in a sintering furnace at a peak temperature of 730 °C [ 42 , 43 , 44 ]. P-doped poly-Si contacts were fabricated with four different thicknesses (see Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

Effects on Metallization of n+-Poly-Si Layer for N-Type Tunnel Oxide Passivated Contact Solar Cells

Wang,

Gao,

et al. 2024

Materials

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Thin polysilicon (poly-Si)-based passivating contacts can reduce parasitic absorption and the cost of n-TOPCon solar cells. Herein, n+-poly-Si layers with thicknesses of 30~100 nm were fabricated by low-pressure chemical vapor deposition (LPCVD) to create passivating contacts. We investigated the effect of n+-poly-Si layer thickness on the microstructure of the metallization contact formation, passivation, and electronic performance of n-TOPCon solar cells. The thickness of the poly-Si layer significantly affected the passivation of metallization-induced recombination under the metal contact (J0,metal) and the contact resistivity (ρc) of the cells. However, it had a minimal impact on the short-circuit current density (Jsc), which was primarily associated with corroded silver (Ag) at depths of the n+-poly-Si layer exceeding 40 nm. We introduced a thin n+-poly-Si layer with a thickness of 70 nm and a surface concentration of 5 × 1020 atoms/cm3. This layer can meet the requirements for low J0,metal and ρc values, leading to an increase in conversion efficiency of 25.65%. This optimized process of depositing a phosphorus-doped poly-Si layer can be commercially applied in photovoltaics to reduce processing times and lower costs.

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“…Upgrades to boron diffusion equipment can allow a much higher process temperature up to 1050°C, which can significantly reduce the process time. At present, the boron diffused layer is mainly prepared by high‐temperature thermal diffusion, using either boron chloride (BCl 3 ) or BBr 3 as the boron source 50,51 . BCl 3 is a gaseous source, and BBr 3 is a liquid source, but both sources can obtain good sheet resistance uniformity on large industrial silicon wafers.…”

Section: Front‐side Fabrication and Metallisationmentioning

confidence: 99%

Mass production of crystalline silicon solar cells with polysilicon‐based passivating contacts: An industrial perspective

Zhang¹,

Dumbrell²,

Li³

et al. 2022

Progress in Photovoltaics

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Silicon solar cells that employ passivating contacts featuring a heavily doped polysilicon layer on a thin silicon oxide (TOPCon) have been demonstrated to facilitate remarkably high cell efficiencies, amongst the highest achieved to date using a single junction on a silicon substrate. Importantly, it has been shown that the polysiliconbased passivating contacts have a high degree of compatibility with existing mass production processes and toolsets, making them an attractive choice for photovoltaic (PV) cell manufacturers to increase the efficiency of their products. With several large PV manufacturers recently announcing plans to push the TOPCon technology into mass production, we review the significant industrial research and development activities that have been undertaken to push the boundaries of the technology and optimise its integration into the existing mass production pipeline. From an industrial perspective, TOPCon fabrication methodology options as well as necessary technological advances in front-side fabrication, cell metallisation and module integration are discussed. The TOPCon technology development is contextualised in terms of larger trends in PV manufacturing, and we look towards the direction of future industrial development.

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Impact of boron doping on electrical performance and efficiency of n-TOPCon solar cell

Cited by 21 publications

References 48 publications

Field‐representative evaluation of PID‐polarization in TOPCon PV modules by accelerated stress testing

Field‐representative evaluation of PID‐polarization in TOPCon PV modules by accelerated stress testing

Effects on Metallization of n+-Poly-Si Layer for N-Type Tunnel Oxide Passivated Contact Solar Cells

Mass production of crystalline silicon solar cells with polysilicon‐based passivating contacts: An industrial perspective

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