Investigation of positive roles of hydrogen plasma treatment for interface passivation based on silicon heterojunction solar cells

Zhang, Liping; Guo, Wanwu; Liu, Wenzhu; Bao, Jian; Liu, Jinning; Shi, Jing; Meng, Fanying; Liu, Zhengxin

doi:10.1088/0022-3727/49/16/165305

Cited by 25 publications

(20 citation statements)

References 40 publications

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“…Meanwhile, hydrogen elimination occurs more readily due to adequate thermal hydrogen desorption [18], which accounts for the lower total hydrogen content (Ctotal) for I160. In addition, a pronounced increase in Ɛi-max from 21.1 to 24.7 also demonstrates a larger mass density of I160 [19]. To summarize, I160 is more compact and less defective than I120.…”

Section: Resultsmentioning

confidence: 82%

Improved amorphous/crystalline silicon interface passivation for silicon heterojunction solar cells by hot-wire atomic hydrogen during doped a-Si:H deposition

Zhang

Chen

et al. 2019

Applied Surface Science

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Intrinsic/doped stacked hydrogenated amorphous silicon (a-Si:H) are widely used passivation layers for amorphous/crystalline silicon (a-Si/c-Si) heterojunction solar cells. This work reports that hot wire chemical vapor deposition of doped a-Si:H can significantly modify the property of the underlying intrinsic a-Si:H (a-Si:H(i)) as well as a-Si/c-Si interface passivation, which stems from the in-diffusion of highly reactive atomic hydrogen. Fourier transform infrared spectroscopy, spectroscopic ellipsometry and Raman analyses indicate that the underlying a-Si:H(i) films become more compact and less defected as a result of network reconstruction during doped a-Si:H capping. After this reconstruction, underdense a-Si:H(i) films obtained superior passivation quality than widely used dense layers, despite the inferior quality in the initial state. Effective minority carrier lifetime of c-Si passivated by underdense a-Si:H(i) was 19.9 ms, much higher than 15.2 ms in the case of using dense a-Si:H(i). The porous structure of underdense a-Si:H(i) facilitates hydrogen diffusion towards a-Si/c-Si interface and hence a rapid reduction of interface defect densities occurs, accounting for the better passivation quality. SHJ solar cells (160 μm, 156 × 156 mm 2) with industry-compatible process were fabricated, yielding the efficiency up to 23.0% with high Voc values of 741mV.

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Section: Resultsmentioning

confidence: 82%

Improved amorphous/crystalline silicon interface passivation for silicon heterojunction solar cells by hot-wire atomic hydrogen during doped a-Si:H deposition

Zhang

Chen

et al. 2019

Applied Surface Science

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“…Another metric that is used in Figure 1 to understand the ion bombardment effect is the power density; to reduce the damage due to the accelerated ion species, the power density is preferred to be less than or equal to 10 mW/cm 2 . 31 From Figure 1a, we can observe that the increase in dc plasma current increases the Hα intensity linearly when the pressure and H 2 flow are kept constant. The plasma voltage (V p ) remains unaffected by the change in the plasma current.…”

Section: Resultsmentioning

confidence: 99%

“…The Hα intensities reported in Figure are time-averaged intensities obtained from time-resolved OES. Another metric that is used in Figure to understand the ion bombardment effect is the power density; to reduce the damage due to the accelerated ion species, the power density is preferred to be less than or equal to 10 mW/cm 2 …”

Section: Resultsmentioning

confidence: 99%

Correlation between in Situ Diagnostics of the Hydrogen Plasma and the Interface Passivation Quality of Hydrogen Plasma Post-Treated a-Si:H in Silicon Heterojunction Solar Cells

Soman

Nsofor

Das

et al. 2019

ACS Appl. Mater. Interfaces

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Passivation of the interface defect states is crucial to mitigate the recombination losses in silicon solar cells. In this work, we have investigated the role of hydrogen plasma treatment (HPT) to passivate the interfacial defects between crystalline (c-Si) and hydrogenated amorphous silicon (a-Si:H) in silicon heterojunction (SHJ) solar cells. For the first time, we have found a correlation between the dynamic properties of hydrogen plasma and passivation quality of the films by using in situ optical emission spectroscopy and quasi-steady state photoconductance measurement. The optimum condition for saturation of the dangling bonds by HPT has been studied in detail by tuning the excited hydrogen (H) species and ion bombardment energies by controlling physical parameters like plasma current and chamber pressure. We have investigated the role of annealing after HPT to redistribute the H in the post-treated a-Si:H film and have obtained an iV oc of 755 mV, minority carrier lifetime (τ eff ) of 4.6 ms, and SRV of 1.5 cm/s on test structures having only an 10 nm intrinsic a-Si:H layer on textured silicon wafers. The H bond configuration at the interface of a-Si:H and c-Si has been investigated by Fourier transform infrared spectroscopy, which demonstrates improved monohydride bonding in the films after HPT derived from the analysis of microstructure parameter and H concentration values. Raman spectroscopy shows the absence of the nanocrystalline fraction after HPT and verifies reduced coordination defects due to annealing after HPT. The proof of concept has been validated by fabricated SHJ solar cells having a V oc of 729 mV and efficiency of 18.7% after HPT, with the best cell efficiency reaching 20.2% after doped layer optimization. The decrease in reverse saturation current and ideality factor after HPT verifies that the improvement in performance is from reduced recombination losses at the interface due to passivation of defects in midgap states.

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“…The commonly used precursor for intrinsic a-Si:H is silane, and the hydrogen-to-silane dilution ratio has a significant effect on the intrinsic a-Si:H film quality due to abstraction and passivation of dangling bonds by ionized hydrogen . In addition to the deposition process of a-Si:H, the hydrogen can be introduced in the process of post-hydrogen plasma treatment, causing hydrogen diffusion to the heterointerface and improving passivation of the dangling bond . Furthermore, an a-Si:H layer deposited on the Si monocrystal serves as an absorber, conducive to the absorption of an essentially wider radiation spectrum due to the larger bandgap of ∼1.8 eV of the a-Si:H layer …”

Section: Different Structures Of Si Solar Cells and Perovskite/si Tan...mentioning

confidence: 99%

Perovskite/Silicon Tandem Solar Cells: Choice of Bottom Devices and Recombination Layers

et al. 2023

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Perovskite/silicon tandem solar cells have been intensively studied in recent years, and their efficiencies have rapidly increased owing to the numerous efforts in this field. A question about which type of silicon solar cell is the most suitable subcell in tandem devices emerges. Herein, three attractive silicon solar cells are summarized, including passivated-emitter rear-cell (PERC), tunnel oxide passivated contact (TOPCon), and heterojunction (HJT) cells. Their structures and features are elucidated for a clear understanding of the mechanism and potential of optimum performance. Moreover, the characteristics and performance of perovskite/silicon tandem cells with PERC, TOPCon, and HJT subcells are contrasted and discussed. The significant contribution of the passivation layer and structure design on both sides to photovoltaic properties of tandem devices is emphasized. Especially, the recombination layer between two subcells is analyzed in depth in terms of material chemistry, light absorption, and charge transport with a review on preparing the optimized structure.

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Investigation of positive roles of hydrogen plasma treatment for interface passivation based on silicon heterojunction solar cells

Cited by 25 publications

References 40 publications

Improved amorphous/crystalline silicon interface passivation for silicon heterojunction solar cells by hot-wire atomic hydrogen during doped a-Si:H deposition

Improved amorphous/crystalline silicon interface passivation for silicon heterojunction solar cells by hot-wire atomic hydrogen during doped a-Si:H deposition

Correlation between in Situ Diagnostics of the Hydrogen Plasma and the Interface Passivation Quality of Hydrogen Plasma Post-Treated a-Si:H in Silicon Heterojunction Solar Cells

Perovskite/Silicon Tandem Solar Cells: Choice of Bottom Devices and Recombination Layers

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