Hybrid films based on silicon nanowires dispersed in a semiconducting polymer for thin film solar cells: Opportunities and new challenges (original) (raw)
Related papers
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).
Hybrid nanocomposites based on conducting polymer and silicon nanowires for photovoltaic application
2014
Hybrid nanocomposites based on a nanoscale combination of organic and inorganic semiconductors are a promising way to enhance the performance of solar cells through a higher aspect ratio of the interface and the good processability of polymers. Nanocomposites are based on a heterojunction network between poly (2-methoxy-5-(2-ethyhexyl-oxy)-p-phenylenevinylene) (MEH-PPV) as an organic electron donor and silicon nanowires (SiNWs) as an inorganic electron acceptor. Nanowires (NWs) seem to be a promising material for this purpose, as they provide a large surface area for contact with the polymer and a designated conducting pathway whilst their volume is low. In this paper, silicon nanowires are introduced by mixing them into the polymer matrix. Hybrid nanocomposites films were deposited onto ITO substrate by spin coating method. Optical properties and photocurrent response were investigated. Charge transfer between the polymer and SiNWs has been demonstrated through photoluminescence measurements. The photocurrent density of ITO/MEH-PPV:SiNWs/Al structures have been obtained by J-V characteristics. The J sc value is about 0.39 mA/cm 2 .
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.
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.
Hybrid Silicon Nanowires for Solar Cell Applications
Emerging Solar Energy Materials
The global human population has been growing by around 1.1% per year; such growth rate will lead the humanity to cross the 10 billion-people threshold by the end of the first half of this century. Such increase is already putting a huge strain on the nonrenewable sources of energy like fossil fuel, which will run out and come to an end in few decades. Due to these social and economic trends, renewable sources of energy, such as solar cells, have attracted a huge interest as the ultimate alternative to solve humanity's problems. Among several emerging materials, porous silicon nanowires (PSiNWs) become an active research subject nowadays in photovoltaic application mainly due to its good light trapping effect. The etched nanowires obtained by using metal-assisted chemical etching method (MACE) can reach a low reflection in the visible range. Recently, hybrid silicon nanowires/organic solar cells have been studied for low-cost Si photovoltaic devices because the Schottky junction between the Si and organic material can be formed by solution processes at low temperature. In this chapter, we will present the synthesis of SiNWs and the last progress on the fabrication of hybrid solar cells using various organic semiconductors.
Silicon Nanowire/P3HT Hybrid Solar Cells: Effect of the Electron Localization at Wire Nanodiameters
Energy Procedia, 2012
Photoactive hybrid films based on n type silicon nanowires [SiNWs] dispersed in poly(3-hexylthiophene) [P3HT], a p type conjugated polymer known for its good ordering properties, have a main interest for the production of photovoltaic films at a limited cost. Silicon nanowires synthesized at high yield by the oxide assisted growth technique have been dispersed in tetrahydrofuran: THF, and mixed with a P3HT solution in THF to form a blend of the inorganic-organic components in the appropriate proportions. The blend of SiNWs and P3HT have been deposited by spin coating on PEDOT-PSS/ITO substrates leading to the production of 100 nm thick SiNWs/P3HT thin layers of controlled compositions. The quenching of the P3HT fluorescence has shown the effective dissociation of the photogenerated pairs for an optimum composition of 6 SiNWs vol. % in the blend, which is in accordance with the low percolation threshold expected from the high aspect ratio of the nanowires. Current/voltage experiments under illumination have however led to collected photocurrents remaining limited to some 10 ∝ A/cm 2 whereas an interesting open circuit voltage of 0.65 V was obtained. It has been possible from surface potential decay experiments to assign the main limiting process to the low electron transport along nanowires of diameter smaller than 10 nm, whereas easy hole transport in the P3HT thickness was obtained. The high densities of silicon surface states acting as electron traps can simultaneously account for efficient charge pair dissociation and low photocurrents in nanosized structures.
Progress in Photovoltaics: Research and Applications, 2013
Silicon nanowires (SiNWs) combined with a conducting polymer are studied to constitute a hybrid organic/inorganic solar cell. This type of cell shows a particularly high interfacial area between SiNWs and the polymer so that interfacial control and interface optimization are required. For that purpose, we terminated the SiNW surfaces with well selected functional groups (molecules) such as native oxide (hereinafter SiO 2 -SiNW), hydrogen (hereinafter H-SiNW) and methyl (hereinafter CH 3 -SiNW). A radial hetero-junction solar cell is formed, and the cell parameters with and without interface control by functionalization with molecules are compared. Electronically, the three surfaces were close to flat-band conditions. The CH 3 -SiNW, H-SiNW and SiO 2 -SiNW produced a surface dipole of À0.12, +0.07 and 0.2 eV and band bending of 50, 100 and 170 meV, respectively. The surface properties of functionalized SiNWs are investigated by photoelectron yield (PY) and photoemission spectroscopy. PY studies on functionalized SiNWs are presented for the first time, and our results show that this type of measurement is an excellent option to carry out interface optimization of NWs for envisaged nanoelectronic and photonic applications. The solar cell efficiency is increased dramatically after terminating the surface with CH 3 molecules due to the decrease of the defect emission. The differently functionalized SiNW surfaces showed identical absorbance, reflectance and transmission so that a change in PY can be attributed to the Si-C bonds at the surface. This finding permits the design of new solar cell concepts.
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.
A Non-Oxidative Approach Towards Hybrid Silicon Nanowire- Based Solar Cell Heterojunctions
Hybrid Materials, 2014
A general method for the non-oxidative termination of silicon nanowires (Si NWs) is reviewed. Oxide-free Si NW have been successfully alkylated in the lab using a two-step chlorination/alkylation process. The distinctive properties of the resulting Si NW have been taken advantage of by integrating the Si NWs into functional devices such as solar cells. Moreover, molecularly terminated Si NWs exhibit lower defect density emissions than unmodified Si NWs. This, in part, explains the better performance of the molecularly terminated Si NW-based solar cells. Solar cells that use organic-inorganic hybrid Si NWs as absorbers show an increased open-circuit voltage (V oc ), an increased short-circuit current (J sc ) and a higher fill factor (FF). The aim of chemical functionalization is to protect Si NWs from extensive oxidation, add functionality and to adjust surface electronic properties such as the work function, surface Fermi level and band bending. The stability of the terminated of Si NWs was found to be dependent on the molecular chain length, molecular coverage, interaction type (π-π or σ-σ), surface energy and Si NW diameter.