Direct growth and photoluminescence of silicon nanowires without catalyst

Al-Ruqeishi, Majid S.; Nor, Roslan Md; Amin, Yusoff Mohd; Al-Azri, Khalifa

doi:10.1016/j.arabjc.2013.07.032

Cited by 11 publications

(7 citation statements)

References 42 publications

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“…The Si–(O) 2 –Si (peroxo), Si–OH (hydroxyl), and Si–O–Si (oxy) bonds at the surface contribute to the observed strong emission. Similar strong photoluminescence peaks in the visible region have been observed in the past for Si nanowires and for porous silicon as well. The CoS/T-Si composite, however, exhibits a profile similar to that of T-Si.…”

Section: Resultssupporting

confidence: 86%

CoS Nanoflakes on Textured Silicon Coupled with Antimony-Decorated Tungsten Oxide for Efficient Liquid Junction Solar Cells

Maity

Kaur

Ghosal

et al. 2022

ACS Appl. Nano Mater.

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A unique liquid junction solar cell (LJSC) based on p-type hole-transporting CoS nanoflakes tethered to n-type textured silicon (T-Si) with pyramidal structures as photoanodes has been fabricated. A ferrocene/ferrocenium (Fc/Fc+) redox couple electrolyte and an electrocatalytic counter electrode film (CE) of antimony nanostructures anchored to tungsten oxide (SbNSs/WO3) are used in the cell. The cell delivers a power conversion efficiency (PCE) of ∼8.4%, which is superior by ∼97% to the LJSCs without CoS and SbNSs. CoS nanoflakes function as independent photosensitizers, generate electron/hole pairs, and increase photocurrents. They also facilitate photo-generated hole transport from T-Si to Fc and suppress charge recombination, leading to an improvement in PCE by ∼82% compared to pristine T-Si. Simultaneously, the composite of SbNSs/WO3 outperforms both SbNSs and WO3 due to better electrocatalytic activity and low overpotential for Fc+ reduction at the CE/Fc+ interface. The CoS/T-Si/Fc/Fc+/SbNSs/WO3 LJSC architecture results in a stable, reproducible performance wherein exposure to extended illumination results in a moderate loss in the PCE, indicating that this strategy of using CoS and Sb can be applied to other hybrid or tandem silicon-based solar cells.

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Section: Resultssupporting

confidence: 86%

CoS Nanoflakes on Textured Silicon Coupled with Antimony-Decorated Tungsten Oxide for Efficient Liquid Junction Solar Cells

Maity

Kaur

Ghosal

et al. 2022

ACS Appl. Nano Mater.

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“…The formation of Si–O–H, Si–O–O–Si, and Si–O–Si bonds occurs at the surfaces, and the energy levels of these defects lie at values that are positioned above the conduction band minimum, which explains the higher energy electronic transitions and hence the emission in the visible region. Similar observations have been made in the past for 1D-SiNWs prepared without a catalyst . In another study on SiNWs prepared by laser ablation at high temperature, the emission in the visible region was attributed to the defect states produced by the amorphous silicon oxide layer formed over crystalline SiNWs .…”

Section: Resultsmentioning

confidence: 99%

“…Similar observations have been made in the past for 1D-SiNWs prepared without a catalyst. 34 In another study on SiNWs prepared by laser ablation at high temperature, the emission in the visible region was attributed to the defect states produced by the amorphous silicon oxide layer formed over crystalline SiNWs. 35 More experimental evidence for the presence of defect states was obtained through the deconvolution of the core level Si2p XPS spectrum, shown in the Supporting Information (as Figure S6).…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of Cuprous Oxide Nanocubes and Antimony Nanorods on the Performance of Silicon Nanowire-Based Quasi-Solid-State Solar Cell

2022

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Antimony nanorods (SbNRs) anchored to vertically aligned SiNWs serve as cosensitizers and enhance the light absorption of NWs, and their favorably positioned valence band (VB) coupled with their p-type semiconducting nature allows fast hole extraction from SiNWs. Photocorrosion of SiNWs is effectively prevented by a monolayer of N-[3-(trimethoxysilyl)propyl]aniline (TMSPA). Upon assembling a quasi-solid-state solar cell with a SbNRs@TMSPA@SiNW photoanode, a triiodide− iodide (I 3 − /I − ) redox couple-based gel encompassing dispersed p-type cuprous oxide nanocubes (Cu 2 O NCs) as the hole transport material. and an electrocatalytic NiO as the counter electrode, a power conversion efficiency (PCE) of 4.7% (under 1 sun) is achieved, which is greater by 177% relative to an analogous cell devoid of the Cu 2 O NCs and SbNRs. SbNRs at the photoanode maximize charge separation and suppress electron−hole and electron−I 3 − recombination at the photoanode/electrolyte interface, thereby improving the overall current collection efficiency. Concurrently, the Cu 2 O NCs facilitate hole scavenging from SbNRs or SiNWs and relay them rapidly to the I − ions in the electrolyte. Optically transparent and mesoporous NiO with a VB conducive to accepting electrons from FTO permits abundant interaction with I 3 − ions. The high PCE is a cumulative outcome of the synergistic attributes of SbNRs, Cu 2 O NCs, and NiO. The SbNRs@TMSPA@SiNWs/Cu 2 O-gel/ NiO solar cell also exhibits a noteworthy operational stability, for it endures 500 h of continuous 1 sun illumination accompanied by an ∼24.4% drop in its PCE. The solar cell architecture in view of the judiciously chosen components with favorable energy level offsets, semiconducting/photoactive properties, and remarkable stability opens up pathways to adapt these materials to other solar cells as well.

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“…The fluorescence spectrum of SiNW (Figure 5a) shows broad emission from 400 to 550 nm with λ max at 430 nm at an excitation wavelength (λ ex ) of 320 nm. SiNWs are characterized by a large surface-to-volume ratio, which allows for water molecules, oxygen radicals, and hydroxyl groups to be adsorbed onto nanowire surfaces during their growth to result in the formation of the following bonds:  Si−O−H, Si− 27 The electronic transitions between the energy states corresponding to these surface defects on SiNWs give rise to the observed multiple emission peaks in the visible region. PCDTBT shows two strong peaks in the visible region with λ max at 418 nm, followed by a broad plateaued emission with λ mid(max) at ∼460 nm, tapering off gradually at ∼550 nm.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Efficient Charge Separation Enabled by N-Doped Graphene Quantum Dots and PCDTBT for a High-Performance Silicon Nanowire Solar Cell

Maity

Kolay

Deepa

2021

ACS Appl. Energy Mater.

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Light absorption by n-silicon nanowires (SiNWs) grown by a chemical etching method is augmented by tethering photoresponsive and highly luminescent nitrogen-doped graphene quantum dots (N-GQDs) and poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) to a SiNW array. The resultant N-GQDs@PCDTBT@SiNW photoanode affords a wide, continuous, and intense absorption band spanning from ∼350 to 1200 nm wavelength range, enabling maximum light uptake, with a work function of ∼4.74 eV, deep enough to not serve as a charge-trapping state. Under illumination, efficient charge separation in this ternary composite is ensured by the p-type semiconducting nature of N-GQDs with a shallow valence band (VB) that allows for rapid hole extraction from the VBs of SiNW and PCDTBT and their rapid relay to the bromide ions in the electrolyte. This is simultaneously accompanied by fast, excited electron injection from N-GQDs and PCDTBT to the SiNW via a cascade process, thus minimizing back electron transfer to the tribromide ions. When the N-GQDs@PCDTBT@SiNW photoanode is coupled with a highly electrocatalytic and electrically conductive multiwalled carbon nanotube (MWCNT)@C-fabric counter electrode and a bromine/bromide electrolyte, a power conversion efficiency of 13.18% is achieved for this liquid junction solar cell, which is significantly enhanced compared to that of the SiNW/HBr,Br2/C-fabric cell (4.37%). The roles of N-GQDs, PCDTBT, and MWCNTs are independently quantified to explain the observed solar cell performance.

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Direct growth and photoluminescence of silicon nanowires without catalyst

Cited by 11 publications

References 42 publications

CoS Nanoflakes on Textured Silicon Coupled with Antimony-Decorated Tungsten Oxide for Efficient Liquid Junction Solar Cells

CoS Nanoflakes on Textured Silicon Coupled with Antimony-Decorated Tungsten Oxide for Efficient Liquid Junction Solar Cells

Effect of Cuprous Oxide Nanocubes and Antimony Nanorods on the Performance of Silicon Nanowire-Based Quasi-Solid-State Solar Cell

Efficient Charge Separation Enabled by N-Doped Graphene Quantum Dots and PCDTBT for a High-Performance Silicon Nanowire Solar Cell

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