A Kinetic Monte Carlo approach to study transport in amorphous silicon/crystalline silicon HIT cells

Muralidharan, Pradyumna; Vasileska, Dragica; Goodnick, Stephen M.; Bowden, Stuart

doi:10.1109/pvsc.2015.7356048

Cited by 7 publications

(5 citation statements)

References 3 publications

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“…As mentioned in the introduction, defect-induced states in semiconductors are a critical factor affecting the efficiency of optoelectronic devices such as solar cells. These states play a key role in carrier recombination, carrier trapping, and carrier transport. − Since the atomic structure changes dramatically going from c-Si to a-Si along the growth direction, it is expected that the density of localized defect states and the orbital localization of the electronic states also change along this direction. Therefore, we also investigate how the density of defect states and the orbital localization changes as the phase gradually changes from c-Si to a-Si and as H is added to the system.…”

Section: Resultsmentioning

confidence: 99%

Role of Hydrogen in the Electronic Properties of a-Si:H/c-Si Heterostructures

Meidanshahi¹,

Vasileska²,

Goodnick³

2021

J. Phys. Chem. C

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In this paper, we explore the effect of H and its bonding configurations on the defect state density and orbital localization of hydrogenated amorphous Si (a-Si:H)/crystalline Si (c-Si) heterostructures using density functional theory (DFT) studies of model interfaces between amorphous silicon (a-Si)/a-Si:H and c-Si. To model the atomic configuration of a-Si on c-Si, melting and quenching simulations were performed using classical molecular dynamics. Different hydrogen contents were inserted into a-Si in different bonding configurations followed by DFT relaxation to create stable structures of a-Si:H representative of hydrogenated a-Si on crystalline Si surfaces. In contrast to typical Si heterojunctions (e.g., Si/SiO2, where the defect density is maximum at the interface), we find that the defect state density is low at the interface and maximum in the bulk of a-Si. Structural analysis shows that in these configurations, H atoms do not necessarily bond to dangling bonds or to interface atoms. However, they are able to significantly change the atomic structure of the heterostructure and consequently decrease the density of defect states and orbital localization in the a-Si layer, particularly at the interface of a-Si/c-Si. The general form of the simulated defect state distribution demonstrates the passivating role of a-Si:H on c-Si substrates.

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Section: Resultsmentioning

confidence: 99%

Role of Hydrogen in the Electronic Properties of a-Si:H/c-Si Heterostructures

Meidanshahi¹,

Vasileska²,

Goodnick³

2021

J. Phys. Chem. C

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“…using the KMC method to study transport across the a-Si:H (i) layer. [24][25][26] F I G U R E 3 Energy distribution function calculated by the EMC at (a) the a-Si:H(i)/c-Si heterointerface and (b) in the low-field quasineutral c-Si bulk, $100 nm away from the a-Si:H (i)/c-Si heterointerface…”

Section: Kinetic Monte Carlomentioning

confidence: 99%

“…We have previously reported our KMC algorithm in detail in Muralidharan et al 24 We consider multi‐phonon processes for injection into the a‐Si:H(i) barrier, defect to defect (hopping) transitions for transport inside the a‐Si:H(i) barrier layer, and a multi‐phonon defect emission and Poole‐Frenkel emission for extraction from the a‐Si:H(i) barrier (shown in Figure 6). 24 We have previously reported preliminary results using the KMC method to study transport across the a‐Si:H(i) layer 24–26 …”

Section: Theoretical Modelmentioning

confidence: 99%

Modeling of transport in carrier‐selective contacts in silicon heterojunction solar cells

Muralidharan

Goodnick

Vasileska

2021

Progress in Photovoltaics

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High‐performance silicon heterojunction (SHJ) solar cells use carrier‐selective contact structures based on hydrogentated amorphous Si (a‐Si:H) to maximize collection of photogenerated carriers. The high open circuit voltages observed experimentally in SHJ cells require that the carrier‐selective contacts provide selectivity and passivation. However, a microscopic understanding of the dynamics of carrier transport through the a‐Si layer is currently lacking. In this paper, we explicitly simulate the transport of holes across the a‐Si:H(i) layer using a novel kinetic Monte Carlo approach. The hole‐selective contact structure investigated in this paper uses p‐type doped a‐Si:H(p) and intrinsic a‐Si:H(i) on an n‐type crystalline silicon wafer, where the selectivity is provided by the a‐Si:H(p) and the passivation is provided by the a‐Si:H(i). However, in addition to the passivation provided by the a‐Si:H(i), this layer also creates a potential barrier to the collection of photogenerated holes. There have been experimental studies in the literature that have suggested that multi‐phonon processes are the main transport mechanism that assists in the transport of holes across the intrinsic a‐Si:H barrier. Simulations presented here show that multi‐phonon injection of holes into the a‐Si:H(i) layer is the rate limiting step for transport across the a‐Si:H(i) layer. Our results indicate that multi‐phonon transport is strongly dependent on the electric field at the a‐Si:H(i)/c‐Si heterointerface as well. Transport simulations presented in this paper are consistent with experimental findings that multi‐phonon processes limit transport across the a‐Si:H(i) layer and are responsible for photocurrent suppression at the a‐Si:H(i)/c‐Si heterointerface when these processes are slower than the associated incident hole flux due to photo‐excitation.

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“…The KMC approach has assisted to create essential results in experimental data by nearly reproducing charge movement, 84 carrier mobility, geminate reintegration, 85 and bimolecular reintegration 83 . This approach has remained a functional instrument for examining, comprehending, and enhancing the performance of OSCs 86‐88 and silicon solar cells 89,90 …”

Section: Current Status Of Perovskite Solar Cells Modellingmentioning

confidence: 99%

“…83 This approach has remained a functional instrument for examining, comprehending, and enhancing the performance of OSCs [86][87][88] and silicon solar cells. 89,90 The KMC approach, based on likely transition rates, gives a more practical 3D model by looking into physical operations like charge formation, charge movement, and charge reintegration in PSCs. Modelling and simulation of entire PSCs employing the KMC method have not been presented by any researcher.…”

Section: Atomistic Modelsmentioning

confidence: 99%

An overview of the mathematical modelling of perovskite solar cells towards achieving highly efficient perovskite devices

et al. 2020

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Summary Researchers have at different times focused on designing perovskite solar cells (PSCs) that are flexible yet highly efficient, to enable the fabrication of portable photovoltaic solar cell (PVSC) devices in large quantities. This upcoming organometal trihalide perovskite has high tendencies of being a highly efficient, yet inexpensive solar cell. This is because the solution processing method is carried out at a reduced temperature and increased solar to electricity conversion efficiency (>25%) obtained within few innovative years. The nanostructured morphology and film quality is essential in obtaining functional power conversion efficiency. It could be a great task for the two characteristics to be present, especially within solutions where very good films are in contact with smooth morphological surfaces. A fast increase in the energy conversion efficiency of these PSCs incorporated with metal halides has been recorded. The next line of research should be to extend the existing models to 3D explicit models of the meso‐structured layer, to verify the 1D effective medium method discussed in the literature. Several models have been discussed to that effect. This review intensively discusses several perovskite models in a bid to understand PSCs. The challenges and future perspectives have also been highlighted.

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A Kinetic Monte Carlo approach to study transport in amorphous silicon/crystalline silicon HIT cells

Cited by 7 publications

References 3 publications

Role of Hydrogen in the Electronic Properties of a-Si:H/c-Si Heterostructures

Role of Hydrogen in the Electronic Properties of a-Si:H/c-Si Heterostructures

Modeling of transport in carrier‐selective contacts in silicon heterojunction solar cells

An overview of the mathematical modelling of perovskite solar cells towards achieving highly efficient perovskite devices

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