Hybrid nanocomposites based on conducting polymer and silicon nanowires for photovoltaic application (original) (raw)
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Journal of Luminescence, 2015
We investigate the effects of Si nanowires surface modification with polystyrene (PS) on the performance of bulk heterojunction hybrid solar cells based on poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and PS-SiNWs. The optical, electrical and morphological properties of these hybrid nanocomposites have been investigated. Due to charge transfer efficiency, improved electrical coupling between SiNWs and MEH-PPV and homogeneous dispersion of functionalized SiNWs, the performance of studied photovoltaic structure shows a significant improvement with the progressive addition of PS-SiNWs. With polystyrene surrounded SiNWs as acceptor materials, the device typically shows a J SC of 7.36 mA/cm 2 , V OC of 0.87 V and a FF of 48% for the composition MEH-PPV:PS-SiNWs (1:4).
Synthetic Metals, 2012
Hybrid devices based on silicon nanowires dispersed in poly(hexylthiophene: P3HT) thin films have been realized. The different steps, starting from the production of n type silicon nanowire, dispersion of the organic-inorganic components in solution to produce hybrid thin films, which have been integrated in simple photovoltaic diode structures, have been developed. The n type doping of the nanowires is indicated by Raman spectroscopy whereas their crystalline structure is shown by HRTEM. A broadening of the silicon absorption spectrum towards the near infrared is induced by an electronic confinement effect for nanowire diameters of the order of 10 nm. Effective dissociation of the photogenerated charge pairs is shown by a partial quenching of P3HT photoluminescence with increasing SiNWs content, whereas an open circuit voltage of 0.68 V is deduced from the electrical characteristics under visible light illumination. However photocurrents remain low for the investigated material combinations. The high series resistance appears the most critical point limiting the device performances. The high densities of SiNWs electronic surface states acting as trapping centers can account for the large reverse current. To confirm the high potential of this new type of hybrid films for energy conversion, improvements are needed for a better control of the silicon nanowire/polymer interface, which appears the critical point.
Bulk Heteroj unction Organic-Inorganic Photovoltaic Cell Based on Doped Silicon Nanowires
CRC Press eBooks, 2019
Heterojunction photovoltaic devices were fabricated using single crystal silicon nanowires and the organic semiconductor regioregular poly-(3-hexyl thiophene) (RR-P3HT). N-type nanowires were first grown on an nþ silicon substrate by the vapor-liquid-solid (VLS) method. Devices were then fabricated by filling the gap between the nanowires and a transparent indium tin oxide (ITO) glass electrode with a polymer. For initial devices the gap was filled with P3HT deposited from chlorobenzene solution. Device performance indicates that both silicon and P3HT act as absorbers for photovoltaic response, but that photocurrents were very low due to high series resistance in the cell. A second type of device was fabricated by depositing a thin layer of P3HT on the grown nanowires by dip coating from a dilute solution, and then filling the voids between nanowires and the transparent electrode with the conductive polymer poly-[3,4-(ethylenedioxy)thiophene]: poly-(styrene sulfonate) (PEDOT:PSS). The relatively high mobility of this organic conductor results in much higher photocurrents in photovoltaic cells, but results in a dip in the spectral response of the cells in the blue-green region due to light absorption in the conducting polymer. These materials show promise for efficient low-cost photovoltaic devices, but the cell geometry and materials interfaces will need to be optimized to reach their potential.
Bulk heterojunction organic-inorganic photovoltaic cells based on doped silicon nanowires
Journal of Experimental Nanoscience, 2008
Heterojunction photovoltaic devices were fabricated using single crystal silicon nanowires and the organic semiconductor regioregular poly-(3-hexyl thiophene) (RR-P3HT). N-type nanowires were first grown on an nþ silicon substrate by the vapor-liquid-solid (VLS) method. Devices were then fabricated by filling the gap between the nanowires and a transparent indium tin oxide (ITO) glass electrode with a polymer. For initial devices the gap was filled with P3HT deposited from chlorobenzene solution. Device performance indicates that both silicon and P3HT act as absorbers for photovoltaic response, but that photocurrents were very low due to high series resistance in the cell. A second type of device was fabricated by depositing a thin layer of P3HT on the grown nanowires by dip coating from a dilute solution, and then filling the voids between nanowires and the transparent electrode with the conductive polymer poly-[3,4-(ethylenedioxy)thiophene]: poly-(styrene sulfonate) (PEDOT:PSS). The relatively high mobility of this organic conductor results in much higher photocurrents in photovoltaic cells, but results in a dip in the spectral response of the cells in the blue-green region due to light absorption in the conducting polymer. These materials show promise for efficient low-cost photovoltaic devices, but the cell geometry and materials interfaces will need to be optimized to reach their potential.
Simple Approach of Fabricating High Efficiency Si Nanowire/Conductive Polymer Hybrid Solar Cells
IEEE Electron Device Letters, 2011
We present a simple approach of fabricating highefficiency hybrid solar cells based on silicon nanowires (SiNWs) and a conductive polymer, poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS). PEDOT:PSS is directly spin coated on vertical SiNW arrays fabricated by electroless chemical etching to form a core-sheath heterojunction. A silver grid is used as the top anode. Compared to a planar Si/PEDOT:PSS cell, the power conversion efficiency of a 1-cm 2 SiNW/PEDOT:PSS cell increases greatly from 6.2% to 9%. Cells with different SiNW lengths are also studied, and it is found that enhanced aggregation of longer SiNWs leads to poor surface coverage by PEDOT and, hence, degraded solar cell characteristics.
Japanese Journal of Applied Physics, 2012
We demonstrate high-efficiency hybrid solar cells based on heterojunctions formed between n-type silicon nanowires (SiNWs) and p-type organic semiconductors fabricated using a simple solution-based approach. Two types of devices have been fabricated with different organic materials used, namely poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and a small molecule, 2,2 0 ,7,7 0-tetrakis(N,N-di-4methoxyphenylamino)-9,9 0-spirobifluorene (Spiro-OMeTAD). The cells are characterized and compared in terms of their physical characteristics and photovoltaic performance. Using SiNWs of the same length of 0.35 m, it is found that the SiNWs/Spiro cells exhibit a power conversion efficiency of 10.3%, which is higher than the 7.7% of SiNWs/PEDOT cells. The results are interpreted in terms of the ability of the two organic semiconductors to fill the gaps between the SiNWs and the optical reflectance of the samples. The degradation of the SiNWs/Spiro cells is also studied and presented.
2012
Nanocomposites of various conducting polymers and porous silicon have been successfully fabricated by the electrochemical and spin coating techniques. Porous silicon template was firstly synthesized by the galvanostatic anodization of silicon wafer in HF-based solution, followed by the electrochemical polymerization of polypyrrole (PPy), polyaniline (PAn) and polythiophene (PTh). The results of the electropolymerization reveal that the polymers are infiltrated homogeneously inside the nanopores. The deposition starts from the pore bottom and propagates towards the pore opening. The deposition of Poly(2methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene) MEH-PPV was also performed into the porous silicon matrix using the spin coating technique. As-formed nanocomposites have been fully characterized using various techniques including, SEM, XRD, FTIR. The photoluminescence behavior was examined and evaluated.
Si Nanowires Organic Semiconductor Hybrid Heterojunction Solar Cells Toward 10% Efficiency
ACS Applied Materials & Interfaces, 2012
High-efficiency hybrid solar cells are fabricated using a simple approach of spin coating a transparent hole transporting organic small molecule, 2,2′,7,7′-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene (Spiro-OMeTAD) on silicon nanowires (SiNWs) arrays prepared by electroless chemical etching. The characteristics of the hybrid cells are investigated as a function of SiNWs length from 0.15 to 5 μm. A maximum average power conversion efficiency of 9.92% has been achieved from 0.35 μm length SiNWs cells, despite a 12% shadowing loss and the absence of antireflective coating and back surface field enhancement. It is found that enhanced aggregations in longer SiNWs limit the cell performance due to increased series resistance and higher carrier recombination in the shorter wavelength region. The effects of the Si substrate doping concentrations on the performance of the cells are also investigated. Cells with higher substrate doping concentration exhibit a significant drop in the incident photons-to-current conversion efficiency (IPCE) in the near infrared region. Nevertheless, a promising short circuit current density of 19 mA/cm 2 and IPCE peak of 57% have been achieved for a 0.9 μm length SiNWs cell fabricated on a highly doped substrate with a minority-carrier diffusion length of only 15 μm. The results suggest that such hybrid cells can potentially be realized using Si thin films instead of bulk substrates. This is promising towards realizing low-cost and high-efficiency SiNWs/organic hybrid solar cells.
Effect of thermal treatments on the properties of PVK/silicon nanowires films for hybrid solar cells
Synthetic Metals, 2011
Hybrid solar cells based on blends of poly(N-vinylcarbazole) (PVK) and silicon nanowires (SiNWs) as electron donor and electron acceptor have been fabricated. The effects of thermal annealing on the photoluminescence and device performances of hybrid photovoltaic cells have been investigated. The influence of the annealing temperature and time on the charge transfer process between PVK and SiNWs has been investigated by the quenching of the PVK photoluminescence in correlation with the morphology changes of the hybrid layer which has been characterized by scanning electron microscopy. The photovoltaic parameters have been significantly improved by heat treatment. The device performance enhancement obtained under optimized annealing temperature and time is mainly due to improved donor/acceptor morphology in the active layer strongly affecting the transport pathways for free charges and contact to the electron-collecting electrode.