Molecular monolayers for conformal, nanoscale doping of InP nanopillar photovoltaics

Cho, Kee; Ruebusch, Daniel J.; Lee, Min Hyung; Moon, Jae Hyun; Ford, Alexandra C.; Kapadia, Rehan; Takei, Kuniharu; Ergen, Onur; Javey, Ali

doi:10.1063/1.3585138

Cited by 60 publications

(53 citation statements)

References 18 publications

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“…As opposed to the top-down method, bottom-up fabrication of nanostructures is an enticing approach to fabricate nanostructures without using costly processes such as lithography and dry-etching. [ 5,17,22,32,51,63,64,[74][75][76][77] As an example, Fan et al reported ordered arrays of Germanium (Ge) dual-diameter Nanopillars (DNPLs) with different diameters at the tip and base fabricated inside self-organized anodic aluminum oxide (AAO) templates. Such DNPLs presented an impressive absorption of 99% of the incident light over a wavelength ranging from 300 to 900 nm with a thickness of only 2 µm.…”

Section: Brief Review Of Light Harvesting With Nanostructuresmentioning

confidence: 99%

Progress and Design Concerns of Nanostructured Solar Energy Harvesting Devices

Leung

Zhang

Tavakoli

et al. 2016

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Integrating devices with nanostructures is considered a promising strategy to improve the performance of solar energy harvesting devices such as photovoltaic (PV) devices and photo-electrochemical (PEC) solar water splitting devices. Extensive efforts have been exerted to improve the power conversion efficiencies (PCE) of such devices by utilizing novel nanostructures to revolutionize device structural designs. The thicknesses of light absorber and material consumption can be substantially reduced because of light trapping with nanostructures. Meanwhile, the utilization of nanostructures can also result in more effective carrier collection by shortening the photogenerated carrier collection path length. Nevertheless, performance optimization of nanostructured solar energy harvesting devices requires a rational design of various aspects of the nanostructures, such as their shape, aspect ratio, periodicity, etc. Without this, the utilization of nanostructures can lead to compromised device performance as the incorporation of these structures can result in defects and additional carrier recombination. The design guidelines of solar energy harvesting devices are summarized, including thin film non-uniformity on nanostructures, surface recombination, parasitic absorption, and the importance of uniform distribution of photo-generated carriers. A systematic view of the design concerns will assist better understanding of device physics and benefit the fabrication of high performance devices in the future.

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Section: Brief Review Of Light Harvesting With Nanostructuresmentioning

confidence: 99%

Progress and Design Concerns of Nanostructured Solar Energy Harvesting Devices

Leung

Zhang

Tavakoli

et al. 2016

Small

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“…[8,95] However, the prevalence of carrier recombination in nanostructured solar cells results in electrical losses that counteract the optical gains, therefore it is difficult for such devices to exceed the J SC and efficiency of conventional solar cells made using standard AR coatings. [96][97][98][99] Even the world record Si-nanostructured solar cell, made with Al 2 O 3 as an AR and passivation layer, featured a J SC and energy conversion efficiency of only 0.2 mA cm −2 and 0.1% higher than a solar cell made with traditional micropyramidal structures. [9] The fundamental problem is the increased surface recombination of nanostructures, which leads to a corresponding decrease in the Voc of nanostructured solar cells.…”

Section: Optical/electrical Tradeoffs Of Nanostructured Solar Cellsmentioning

confidence: 99%

“…However, its solar efficiency is still lower than that of planar InP homojunction solar cells, which use traditional AR coatings, indicating just how great an impact nanostructures can have on electrical losses and thus the overall device performance. [99,142] Engineering new solar device architectures provides a promising way to exclude the severe surface and Auger recombination effects that compromise nanostructured materials. For example, IBC design has been used to improve efficiency for thick Si solar cells for some time.…”

Section: Device Architecture Engineeringmentioning

confidence: 99%

Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

Wang

2017

Advanced Energy Materials

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For example, the multiple exciton generation (MEG) effect, observed in quantum dots (QDs), could have the potential to boost the Shockley-Queisser efficiency limit from 33.7% to 44.0%. [4,5] Nanostructured absorbers, featuring subwavelength features, can achieve an absorption enhancement factor higher than the conventional ray-optic limit across a broadband range of wavelengths, which opens an entirely new way of designing highly efficient nanostructured solar cells. [6,7] Meanwhile, the utilization of nanostructures can improve carrier collection by promoting the separation of photogenerated carriers and shortening the diffusion length of charge carriers using core-shell architectures. [8] However, despite the advantages of nanostructures, at present the efficiency of these solar cells remains lower than that of first-and second-generation devices. Compared with commercially available Si wafer photovoltaics, whose energy conversion efficiency can reach 25.6%, the record energy conversion efficiency of a nanostructured Si solar cell is only 22.1%, which is still far from the Shockley-Queisser efficiency limit of 32.0%. [9,10] This limited performance is due to the fact that most nanostructures bring accompanying optical or electrical losses to solar cells (Figure 1). [11][12][13][14][15] In fact, most nano-based solar cells have relatively low open-circuit voltages (V OC ) and a disproportionate enhancement of the short-circuit current density (J SC ) compared to the absorption enhancement via light-trapping nanostructures. Therefore, in order to avoid the counterbalance of optical and electrical gains by the accompanying losses associated with nanomaterials, it is necessary to look beyond singularly focused optical or electrical promotion schemes, and instead shift toward the concurrent design of electrical and optical properties using a combined perspective to achieve highly efficient nanostructured solar cells.Thus far, many excellent reviews have summarized different photon management or light-harvesting schemes with the use of nanostructures. [16][17][18][19][20][21][22][23][24] These authors point out that important work remains to ensure that improved optical absorption does not come at the sacrifice of the device's electrical properties. [16,17,[19][20][21][22][23][24] However, there have been few reviews that propose a solution for how to overcome this challenge. Recently, there has been considerable effort to increase both light absorption and the photogenerated carrier collection Recent technological advances in conventional planar and microstructured solar cell architectures have significantly boosted the efficiencies of these devices near the corresponding theoretical values. Nanomaterials and nano structures have promising potential to push the theoretical limits of solar cell efficiency even higher using the intrinsic advantages associated with these materials, including efficient photon management, rapid charge transfer, and short charge collection distances. However, at present the efficiency of...

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“…Monolayer doping is used in an increasing number of applications that require the controlled doping of nanostructures and for achieving ultrashallow surface doping of semiconductors. [ 20–25 ] Advances in monolayer doping provide significant progress in obtaining improved properties, including higher doping densities and various aspects of the monolayer doping method. [ 18,26 ] Monolayer doping involves the thermal fragmentation of the monolayer followed by dopant activation and diffusion.…”

Section: Introductionmentioning

confidence: 99%

Boron Monolayer Doping: Role of Oxide Capping Layer, Molecular Fragmentation, and Doping Uniformity at the Nanoscale

Tzaguy

Karadan

Killi

et al. 2020

Adv Materials Inter

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Doping methodologies using monolayers offer controlled, ex situ doping of nanowires (NWs), and 3D device architectures using molecular monolayers as dopant sources with uniform, self‐limiting characteristics. Comparing doping levels and uniformity for boron‐containing monolayers using different methodologies demonstrates the effects of oxide capping on doping performances following rapid thermal anneal (RTA). Strikingly, for noncovalent monolayers of phenylboronic acid (PBA), highest doping levels are obtained with minimal thermal budget without applying oxide capping. Monolayer damage and entrapment of molecular fragments in the oxide capping layer account for the lower performance caused by thermal damage to the PBA monolayer, which results in transformation of the monolayer source to a thin solid source layer. The impact of the oxide capping procedure is demonstrated by a series of experiments. Details of monolayer fragmentation processes and its impact on doping uniformity at the nanoscale are addressed for two types of surface chemistries by applying Kelvin probe force microscopy (KPFM). These results point at the importance of molecular decomposition processes for monolayer‐based doping methodologies, both during preanneal capping step and during rapid thermal processing step. These are important guidelines to be considered for future developments of appropriate surface chemistry used in monolayer doping applications.

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Molecular monolayers for conformal, nanoscale doping of InP nanopillar photovoltaics

Cited by 60 publications

References 18 publications

Progress and Design Concerns of Nanostructured Solar Energy Harvesting Devices

Progress and Design Concerns of Nanostructured Solar Energy Harvesting Devices

Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

Boron Monolayer Doping: Role of Oxide Capping Layer, Molecular Fragmentation, and Doping Uniformity at the Nanoscale

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