Multiprobe Characterization of Inversion Charge for Self-Consistent Parameterization of HIT Cells

Chavali, Raghu Vamsi Krishna; Khatavkar, Sanchit; Kannan, C. Ramesh; Kumar, Vijay; Nair, Pradeep R.; Gray, J.L.; Alam, Muhammad Ashraful

doi:10.1109/jphotov.2014.2388072

Cited by 22 publications

(13 citation statements)

References 40 publications

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“…The J Diode obtained from experiments (□) and the compact model (−), indicating the current saturation at

V_{1}^{Dark}

(marked in green) for A, voltages>0.5 V for low‐quality samples and C, >0.7 V for high‐quality samples . The corresponding J Pho also indicates the expected shift in the rollover voltage at

V_{1}^{Light}

(marked in green) for B, low‐ and D, high‐quality samples.…”

Section: The Physics Of Carrier Collection Encapsulated In a Compact mentioning

confidence: 99%

“…B, Simulated V OC contour plot as a function of front (

N_{IT}^{F}

) and back (

N_{IT}^{B}

) interface defect densities. C, The influence of (i) t i , varied from 5 to 20 nm (ii) Δ E V , varied from 0.37 to 0.47 eV (iii) ϕ P , where p‐layer doping ( N A ) is varied from 2 × 10 18 to 10 19 , on FF of typical SHJ cell light J‐V characteristics [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Status Of High Efficiency Shj Cellsmentioning

confidence: 99%

“…Under this condition, the magnitude of the diode current injected from the front contact into the c‐Si region is dictated by the height of the a‐Si:H valence band spike observed from the front contact (see Figure F). As the bending in a‐Si:H does not change significantly with applied bias (due to the presence of the inversion charge at the interface), the carrier injection also does not change significantly. Hence, the injected diode (dark) current saturates with respect to the applied bias.…”

Section: The Physics Of Carrier Collection Encapsulated In a Compact mentioning

confidence: 99%

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Device physics underlying silicon heterojunction and passivating‐contact solar cells: A topical review

Chavali

Wolf

Alam

2018

Progress in Photovoltaics

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The device physics of commercially dominant diffused-junction silicon solar cells is well understood, allowing sophisticated optimization of this class of devices. Recently, so-called passivating-contact solar cell technologies have become prominent, with Kaneka setting the world's silicon solar cell efficiency record of 26.63% using silicon heterojunction contacts in an interdigitated configuration. Although passivating-contact solar cells are remarkably efficient, their underlying device physics is not yet completely understood, not in the least because they are constructed from diverse materials that may introduce electronic barriers in the current flow.To bridge this gap in understanding, we explore the device physics of passivating contact silicon heterojunction (SHJ) solar cells. Here, we identify the key properties of heterojunctions that affect cell efficiency, analyze the dependence of key heterojunction properties on carrier transport under light and dark conditions, provide a self-consistent multiprobe approach to extract heterojunction parameters using several characterization techniques (including dark J-V, light J-V, C-V, admittance spectroscopy, and Suns-Voc), propose design guidelines to address bottlenecks in energy production in SHJ cells, and develop a process-to-module modeling framework to establish the module's performance limits. We expect that our proposed guidelines resulting from this multiscale and self-consistent framework will improve the performance of future SHJ cells as well as other passivating contact-based solar cells.

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“…The J Diode obtained from experiments (□) and the compact model (−), indicating the current saturation at

V_{1}^{Dark}

(marked in green) for A, voltages>0.5 V for low‐quality samples and C, >0.7 V for high‐quality samples . The corresponding J Pho also indicates the expected shift in the rollover voltage at

V_{1}^{Light}

(marked in green) for B, low‐ and D, high‐quality samples.…”

Section: The Physics Of Carrier Collection Encapsulated In a Compact mentioning

confidence: 99%

“…B, Simulated V OC contour plot as a function of front (

N_{IT}^{F}

) and back (

N_{IT}^{B}

Section: Status Of High Efficiency Shj Cellsmentioning

confidence: 99%

Section: The Physics Of Carrier Collection Encapsulated In a Compact mentioning

confidence: 99%

See 1 more Smart Citation

Device physics underlying silicon heterojunction and passivating‐contact solar cells: A topical review

Chavali

Wolf

Alam

2018

Progress in Photovoltaics

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“…We will use an a-Si-like solar cell [22], [23] and an HIT cell [17], [24]- [26] as the example test cases to show that the principle of superposition can fail in these solar cells under certain conditions. 1) p-i-n Solar Cell: For a p-i-n cell, the assumption that J Photo is independent of bias is no longer valid.…”

Section: B Voltage-dependent Collectionmentioning

confidence: 99%

The Frozen Potential Approach to Separate the Photocurrent and Diode Injection Current in Solar Cells

Chavali

Moore

Wang

et al. 2015

IEEE J. Photovoltaics

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The principle of superposition is commonly utilized in the analysis of current transport under dark and light conditions for several different types of solar cells. However, this principle assumes that the photocurrent is voltage independent and that the diode injection current is generation independent, which restricts its validity. Indeed, the superposition principle cannot be applied to most thin-film solar cells because the above mentioned assumptions are not generally valid. In order to address this issue, a novel numerical modeling approach is described that allows independent computation of the photocurrent and of the diode injection current as components of the total current under illumination. Then, using several test cases, where the principle of superposition breaks down, the usefulness of this modeling approach is demonstrated.

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“…Based on the spatially-resolved light absorption profile, the transport of the photo-generated electrons and holes are solved in a 2D coupled Poisson-drift-diffusion solver Sentaurus TCAD 17 . The electrical properties of the interfaces and bulk layers are adapted from previous work 18 . Finally, Sentaurus automatically accounts for the intrinsic resistance related to current crowding between the metal and heavily doped regions as illustrated in Fig.…”

mentioning

confidence: 99%

Tailoring interdigitated back contacts for high-performance bifacial silicon solar cells

Sun

Zhou

Asadpour

et al. 2019

Applied Physics Letters

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Photovoltaic (PV) cells have become one of the most promising renewable energy technologies. To make PV more competitive with incumbent technologies, higher power output densities are needed. One promising approach is to add bifaciality to existing monofacial PV devices, allowing more output power from the additional reflection of sunlight from the ground (albedo ). For example, bifaciality can be added to Silicon Heterojunction (SHJ) solar cell with Interdigitated Back Contacts (IBC) by opening up the gaps between the back metal contacts, but the optimum gap ( ) that maximizes power output is unknown. In this paper we show that that the optimum gap ( = 1 − (1 + )( ( + )) − 1 2 ) maximizes IBC-SHJ bifacial power output ( ∝ (1 + ) (1 − 2√ ⁄ ), where is the ratio of output power density to power loss due to shadowing and Joule heating, The results are validated by self-consistent finite-element device modeling. For a typical α = 0.3, an optimized bifacial IBC SHJ cell will produce 17% more power output than state-of-the-art monofacial IBC SHJ cells. The results encourage development of bifacial IBC solar cells as a next generation PV technology.The energy output of a solar cell depends on both the solar irradiance absorbed via the photovoltaic effect, as well as its efficiency in converting photo-generated carriers into electricity. Traditional monofacial cells accept light only from the front surface; therefore, reflection from index mismatch and/or a front-contact metallic grid reduces light coupling into cells. Texturing the front surface and/or including an anti-reflection coating addresses the challenge of index mismatch, while interdigitated back-contact cells (IBC) move both n-and p-type contacts to the back to minimize front-grid light reflection. This improved light coupling allows IBC cells to achieve particularly high power output under typical illumination. By inserting high bandgap (Eg) material between absorber and highly recombination active metal contacts, Silicon heterojunction solar cells (SHJ) 1 can provide higher efficiency (η > 25%) and lower temperature coefficients 2 than traditional p-n junction solar cells. Today, despite the fact that recent market forecasts predict the rapid increase in monofacial Passivated Emitter and Rear Contact (PERC) cell production 3,4 , monofacial IBC SHJ cells ranks among the very best high-performance cells, with efficiencies exceeding 26% in experiments 5 .A new solar cell architecture, called bifacial PV, has recently emerged as a promising technological pathway to higher output yields and lower costs 4,6-9 . The bifacial design accepts light from both surfaces, therefore it allows absorption of ground reflected sunlight (albedo) at the rear side of solar cell. The sum of the direct sunlight and the albedo illumination increases photocurrent within the cell. Unfortunately, the benefits of bifacial operation of an IBC SHJ cell are not easily quantifiedafter all, the dense interdigitated grid in the back may only allow a fraction of the albedo (α) light to reach...

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Multiprobe Characterization of Inversion Charge for Self-Consistent Parameterization of HIT Cells

Cited by 22 publications

References 40 publications

Device physics underlying silicon heterojunction and passivating‐contact solar cells: A topical review

Device physics underlying silicon heterojunction and passivating‐contact solar cells: A topical review

The Frozen Potential Approach to Separate the Photocurrent and Diode Injection Current in Solar Cells

Tailoring interdigitated back contacts for high-performance bifacial silicon solar cells

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