Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts

Park, Hyun Jung; Lee, Youngseok; Park, Se Jin; Bae, Soohyun; Kim, Sangho; Oh, Dae Jong; Park, Jinjoo; Kim, Young-Kuk; Guim, Hwanuk; Kang, Yoonmook; Lee, Hae Seok; Kim, Dong Hwan; Yi, Junsin

doi:10.1002/pip.3190

Cited by 20 publications

(12 citation statements)

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“…Silicon heterojunction (SHJ) solar cells combine crystalline silicon (c-Si) as bulk absorber with thin-film silicon technology as transport stacks for high efficiency based on carrier-selective contacts (CSC). SHJ contact stack typically consists of hydrogenated intrinsic amorphous silicon (i-a-Si:H) layer followed by a doped thin-film silicon [1][2][3][4] (eventually alloyed with oxygen [5][6][7][8][9][10][11][12][13][14] or carbon [15][16][17] ) and a transparent conductive oxide (TCO). The purpose of these layers is to provide the so-called contact selectivity by inducing an electric potential inside the c-Si for carrier separation that allows the collection of one type of carriers while repelling the other.…”

Section: Introductionmentioning

confidence: 99%

The role of heterointerfaces and subgap energy states on transport mechanisms in silicon heterojunction solar cells

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Sáez

et al. 2020

Progress in Photovoltaics

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The contact resistivity is a key parameter to reach high conversion efficiency in solar cells, especially in architectures based on the so-called carrier-selective contacts. The importance of contact resistivity relies on the evaluation of the quality of charge collection from the absorber bulk through adjacent electrodes. The electrode usually consists of a stack of layers entailing complex charge transport processes. This is especially the case of silicon heterojunction (SHJ) contacts. Although it is known that in thin-film silicon, the transport is based on subgap energy states, the mechanisms of charge collection in SHJ systems is not fully understood yet. Here, we analyse the physical mechanisms driving the exchange of charge among SHJ layers with the support of rigorous numerical simulations that reasonably replicate experimental results.We observe a connection between recombination and collection of carriers. Simulation results reveal that charge transport depends on the alignment and the nature of energy states at heterointerfaces. Our results demonstrate that transport based on direct energy transitions is more efficient than transport based on subgap energy states. Particularly, for positive charge collection, energy states associated to dangling bonds support the charge exchange more efficiently than tail states. The conditions for optimal carrier collection rely on the Fermi energy of the layers, in terms of activation energy of doped layers and carrier concentration of transparent conductive oxide. We observe that fill factor (FF) above 86% concurrently with 750-mV open circuit voltage can be attained in SHJ solar cells with ρ c lower than 45 mΩ•cm 2 for p-contact and 20 mΩ•cm 2 for the n-contact. Furthermore, for achieving optimal contact resistivity, we provide engineering guidelines that are valid for a wide range of silicon materials from amorphous to nanocrystalline layers.

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Section: Introductionmentioning

confidence: 99%

The role of heterointerfaces and subgap energy states on transport mechanisms in silicon heterojunction solar cells

Procel

Sáez

et al. 2020

Progress in Photovoltaics

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“…With each development target, various types of silicon cells have been developed. Examples include the back surface field (BSF), passivated emitter rear cell (PERC), passivated emitter rear locally diffused (PERL), passivated emitter rear totally diffused (PERT), [ 175,176 ] heterojunction with intrinsic thin layer (HIT), [ 177 ] interdigitated back contact (IBC), tunnel‐oxide passivated contact (TOPCon), [ 178–181 ] heterojunction back contact (HBC), [ 182 ] polysilicon on oxide (POLO), [ 183 ] and bifacial cell. [ 184 ]…”

Section: Si Cigs and Cdte Solar Cells: Development And Upscaling Himentioning

confidence: 99%

Historical Analysis of High‐Efficiency, Large‐Area Solar Cells: Toward Upscaling of Perovskite Solar Cells

et al. 2020

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1% at 0.4798 cm 2 , and 14.0% at 1.045 cm 2 , respectively, while the corresponding module efficiencies are 25.1% at 866.45 cm 2 , 24.4% at 13 177 cm 2 , 19.2% at 841 cm 2 , 19.0% at 23 573 cm 2 , and 12.3% at 14.322 cm 2 , respectively. [2-4] Silicon modules account for over 90% of the solar cell market share. [5] Although thin-film solar modules compete with silicon solar cells, the efficiency of the former is lower by ≈5 percentage points (%p). [2-4] Recently, a perovskite solar cell was reported, which used an organic metalhalide hybrid material with an ABX 3 perovskite crystal structure as the lightabsorbing layer. [6-8] This type of perovskite solar cell has attracted much attention as a next-generation solar cell. Kojima et al. first reported a perovskite solar cell with an efficiency of 3.8% in 2009. [9] Initially, perovskite solar cells did not receive much attention because of their poor stability and efficiency. However, research has increased since Park and co-workers reported an efficiency exceeding 9% with stability over 500 h in ambient conditions. [10,11] In the last six years, the efficiency of perovskite solar cells increased from 14.1% to 25.2%, which is the thirdhighest single-junction efficiency reported thus far. [2-4] However, perovskite solar cells are facing commercialization issues. For their successful application to the industry, the following problems must first be addressed: [12,13]-Upscaling (high-efficiency, large-area module demonstration)-Stability (performance degradation over times)-Toxicity (lead (Pb) and cesium (Cs) issues). Stability and toxicity problems were introduced relatively early in the literature. [10,11] Immense efforts were devoted to finding the origin of and solution to the degradation of perovskite solar cells. Owing to the dedicated efforts of countless researchers, the degradation factors were identified as the humidity, light, [14,15] heat, [16,17] and electric fields. [12,18] Degradation issues have been addressed with the development of stable perovskite compositions, electron-transfer layers (ETLs) and hole-transfer layers (HTLs), and encapsulations. Several groups have reported perovskite solar cells that passed the International Electrotechnical Commission (IEC) stability test, while Grätzel and co-workers reported a cell that remained stable for one year. [19-22] Thus, stability has been significantly improved. The status and problems of upscaling research on perovskite solar cells, which must be addressed for commercialization efforts to be successful, are investigated. An 804 cm 2 perovskite solar module has been reported with 17.9% efficiency, which is significantly lower than the champion perovskite solar cell efficiency of 25.2% reported for a 0.09 cm 2 aperture area. For the realization of upscaling high-quality perovskite solar cells, the upscaling and development history of conventional silicon, copper indium gallium sulfur/ selenide and CdTe solar cells, which are already commercialized with modules of sizes up to ≈25 000 cm 2 , are reviewed. ...

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“…After depositing intrinsic polysilicon on the chemical tunnel oxide passivated n-type silicon wafer, phosphorus doping was performed in a tube furnace at temperatures in the range of 875-1000 • C using POCl 3 as the source. Implied Voc values were measured after an additional hydrogenation process, which can largely enhance the passivation quality of the TOPCon structure [40]. The lowest value of recombination current density was obtained after phosphorus diffusion at 925 • C, with the time varying from 5 to 25 min, as shown in Figure 3b, and a maximum implied Voc of 730.6 mV was obtained after 10 min diffusion at 925 • C. These high properties of the rear passivated contact structure improve the qualities of the entire bottom cell, even if the front MoO x passivation property is quite low.…”

Section: Molybdenum Oxide Hole Selective Contact Si Solar Cellmentioning

confidence: 99%

Monolithic Perovskite-Carrier Selective Contact Silicon Tandem Solar Cells Using Molybdenum Oxide as a Hole Selective Layer

et al. 2021

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Monolithic perovskite–silicon tandem solar cells with MoOx hole selective contact silicon bottom solar cells show a power conversion efficiency of 8%. A thin 15 nm-thick MoOx contact to n-type Si was used instead of a standard p+ emitter to collect holes and the SiOx/n+ poly-Si structure was deposited on the other side of the device for direct tunneling of electrons and this silicon bottom cell structure shows ~15% of power conversion efficiency. With this bottom carrier selective silicon cell, tin oxide, and subsequent perovskite structure were deposited to fabricate monolithic tandem solar cells. Monolithic tandem structure without ITO interlayer was also compared to confirm the role of MoOx in tandem cells and this tandem structure shows the power conversion efficiency of 3.3%. This research has confirmed that the MoOx layer simultaneously acts as a passivation layer and a hole collecting layer in this tandem structure.

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Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts

Cited by 20 publications

References 67 publications

The role of heterointerfaces and subgap energy states on transport mechanisms in silicon heterojunction solar cells

The role of heterointerfaces and subgap energy states on transport mechanisms in silicon heterojunction solar cells

Historical Analysis of High‐Efficiency, Large‐Area Solar Cells: Toward Upscaling of Perovskite Solar Cells

Monolithic Perovskite-Carrier Selective Contact Silicon Tandem Solar Cells Using Molybdenum Oxide as a Hole Selective Layer

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