Crystallite size dependence of band gap energy for electrodeposited ZnO grown at different temperatures

Marotti, Ricardo E.; Giorgi, P.; Machado, Giovanna; Dalchiele, Enrique A.

doi:10.1016/j.solmat.2006.03.008

Cited by 256 publications

(114 citation statements)

References 13 publications

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“…The band gap energy obtained following this method, Figure 5, is 3.22eV. The values obtained in the two methods are very similar and very close to the accepted room temperature bandgap energy of bulk ZnO, which is between 3.2 and 3.4 eV at room temperature 19 . (200) cristal planes of the cubic gold structure 21 , and the peak at 39.52° is associated to (111) cristal plane of cubic palladium structure 22 .…”

Section: Structural Morphological and Optical Characterization Of Znsupporting

confidence: 71%

ELECTRODEPOSITION OF ZnO NANOROD ARRAYS FOR APPLICATION IN PEROVSKITE BASED SOLAR CELLS

Cataño

Allende

Gómez

2015

J. Chil. Chem. Soc.

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We report a low-cost, free-hole conductor methylammonium lead iodide CH 3 NH 3 PbI 3 (perovskite)/ZnO nanorods (NR) heterojunction solar cell. ZnO nanorod arrays were obtained electrochemically onto transparent conducting oxide (fluor doped tin oxide, FTO) from an aqueous solution of zinc acetate. The ZnO NR were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical transmittance. Solar cell was fabricated forming the perovskite material onto the ZnO thin film. Spin coating of an equimolar mixture of CH 3 NH 3 I and PbI 2 in γ-butyrolactone solution (perovskite precursor solution) leads to CH 3 NH 3 PbI 3 formation on ZnO NR. A graphite-covered FTO/glass was used as a back contact. The photovoltaic performance of the solar cell was characterized at full sun intensity of 100 mW/cm 2 obtaining a shortcircuit current of 1.5 mA/cm 2 , an open circuit voltage of 0.47 V and energy conversion efficiency of 0.16 %.Keywords: Solar cells, Organic-Inorganic Perovskites, Zinc Oxide, Nanorods. INTRODUCTIONEnergy plays an important role in the economic future of countries. This problem is a global issue for our planet, aggravated by the fact that in the forthcoming decades, due to an increasing world population, energy demand will increase significantly. Conservative estimates implies that fossil fuels may be exhausted during the decade of 2040s 1 , with the serious consequences that this entails. It is expected that in future, solar energy will play a major role as an alternative energy source. The Sun provides Earth with as much energy every hour as human civilization uses every year 2 . Therefore, harvesting a small fraction of incident solar irradiation could meet our growing energy demand. Realizing the full potential of this vast energy source requires a new generation of photovoltaics that are both efficient and cost-effective.Nowadays, the cristallyne silicon solar cell corresponds to the most used photovoltaic technology. However, the manufacturing of this kind of solar cell demands a great amount of energy. Purifying and crystallizing the silicon are the most energy intensive parts of the solar cell manufacturing process. In this case the EPBT (Energy Payback Time, the length of time a PV system takes to generate the amount of energy put into system) is as long as 2.7 years.Organic-inorganic perovskite-based solar cells have recently emerged as a transformative photovoltaic (PV) technology. Perovskite solar cells based on titanium dioxide, a CH 3 NH 3 PbI 3 light-absorption layer and spiro-OMeTAD as hole transporting material have achieved power conversion efficiencies as high as 15.0 % 3 , making it competitive with thin-film PV technology. Several reports suggest that solar cells with efficiencies up to 20% are realistically achievable 4-5 . The most attractive aspects of this technology are the simplicity of photoactive layer synthesis and application using benchtop approaches at temperatures less than 100°C. 6 Besides, the perovskite material exhibit optimal characteri...

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Section: Structural Morphological and Optical Characterization Of Znsupporting

confidence: 71%

ELECTRODEPOSITION OF ZnO NANOROD ARRAYS FOR APPLICATION IN PEROVSKITE BASED SOLAR CELLS

Cataño

Allende

Gómez

2015

J. Chil. Chem. Soc.

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“…It is an interesting material for short-wavelength optoelectronic applications owing to its wide band gap 3.37 eV [5][6][7], large bond strength, large exciton binding energy (60 MeV) at room temperature, non toxic and abundant in nature [8][9][10][11][12][13]. Several techniques have been used for the preparation of ZnO thin films, such as sputtering, chemical vapor deposition (MOCVD), pulsed laser ablation (PLD), molecular beam epitaxy (MBE), electrochemical deposition, pyrolysis spray, reactive evaporation, colloidal and sol-gel method [14][15][16][17][18][19]. It is a versatile material that finds applications in various products, such as gas sensor, chemical sensor, biosensor, optical and electrical devices, window materials for displays, the thermal barrier, piezoelectric transducers, solar cells, varistors, laser devices and drug delivery [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Structural and Optical Properties of ZnO and Co Doped ZnO Thin Films Prepared by Sol-Gel

et al. 2018

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We report on ZnO films doped with different Co concentrations (0, 0.5, and 1 wt%) prepared by sol-gel technique in association with dip-coating onto glass substrates. Zinc acetate dehydrate, cobalt acetate, mono ethanolamine were used as starting materials, as well as solvent and stabilizer, respectively. Nanostructured polycrystalline ZnO thin films with different concentrations of Co doping (0, 0.5, and 1 wt%) are prepared for the first time by the sol-gel method and annealed at 500• C for 1 h. The surface morphologies of the ZnO thin films deposited on glass substrate with different concentrations were evaluated by atomic force microscopy. The optical absorption of the films showed a blue shift of the band gap. The photoluminescence signal of the thin films of undoped and Co-doped ZnO presents different bands in the visible region. The electrical conductivity of the sample with 0.5%Co was found to be 4.62 (Ω C m) −1 .

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“…12 are still too large when compared to the value of D, 71 the dispersion of sizes may enhanced the shift when compared with the mean value in a sample. 72 …”

Section: Optical Properties Of Thementioning

confidence: 99%

The Effect of a Sputtered Al-Doped ZnO Seed Layer on the Morphological, Structural and Optical Properties of Electrochemically Grown ZnO Nanorod Arrays

Campo¹,

Navarrete-Astorga

Pereyra³

et al. 2016

J. Electrochem. Soc.

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The effect of both a RF sputtered Al-doped ZnO (AZO) thin film seed layer onto a FTO/glass substrate and its growth time onto the morphological, structural and optical properties of the resulting electrochemically grown ZnO nanorod arrays (NRAs) have been studied. ZnO NRs grown onto the different AZO seed layers exhibit smaller mean diameter and length than those grown onto a bare FTO/glass substrate, but ZnO NR density presents an opposite behavior, by using an AZO seed layer ZnO nanorod density can be increased by a factor of six. ZnO nanorods are highly crystalline with a wurtzite hexagonal structure and with a preferential growth perpendicular to the substrate. The c-axis of most of the ZnO NRs grown onto an AZO seed layer is aligned within ±6 • from the substrate surface normal. Both NRAs mean length and density increases light scattering, without greatly affecting the spectra shape. The diffuse reflectance intensity is more sensitive to NR density variations than to length or diameter variations. NR diameter affects directly the shape of these diffuse reflectance spectra: they red-shifts and broadens when NR mean diameter increases. A small influence in the UV edge due to size quantization may be also present. In recent years, ZnO, a wide bandgap semiconductor with a direct bandgap of about 3.37 eV and high exciton binding energy (60 meV) at room temperature, has attracted increasing interest due to its unique ability to form a variety of nanostructures such as nanowires, nanorods, nanobelts, nanocombs, nanospheres, nano-tetrapods.1,2 Among them, the most interesting are nanorods and nanorod arrays (NRAs) vertically arranged with respect to the substrate.1 These ZnO nanostructures present a pseudo-one dimensional (1D) structure, with an enhanced surface-to-volume ratio and confinement effects.3 ZnO nanorods exhibit fewer defects than its thin-film structure, it is, therefore, a promising material for optoelectronic applications. 4 In fact, recently, single crystal ZnO nanowire and nanorod arrays have emerged as promising building blocks for a new generation of devices in different hi-tech domains such as optoelectronics, gas sensing, field emission, piezoelectrics and solar cells. 2,5,6 In particular, ZnO one dimensional nanostructures are good candidates for photovoltaic applications for three straightforward reasons: i) they have a low reflectivity that enhances the light absorption; ii) relatively high surface to volume ratio that enables interfacial charge separation and iii) fast electron transport along the crystalline 1D nanostructures that improves the charge collection efficiency. In fact, ZnO arrays of 1D nanostructures, such as nanowires and nanotubes, have been widely utilized as they provide a direct conduction pathway for the rapid collection of the photogenerated electrons, 7 reducing the non-radiative recombination and carrier scattering loss dramatically, 8 and providing as well a high junction area.9,10 Moreover, electron transport in the crystalline nanorod is expected to be several orde...

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Crystallite size dependence of band gap energy for electrodeposited ZnO grown at different temperatures

Cited by 256 publications

References 13 publications

ELECTRODEPOSITION OF ZnO NANOROD ARRAYS FOR APPLICATION IN PEROVSKITE BASED SOLAR CELLS

ELECTRODEPOSITION OF ZnO NANOROD ARRAYS FOR APPLICATION IN PEROVSKITE BASED SOLAR CELLS

Structural and Optical Properties of ZnO and Co Doped ZnO Thin Films Prepared by Sol-Gel

The Effect of a Sputtered Al-Doped ZnO Seed Layer on the Morphological, Structural and Optical Properties of Electrochemically Grown ZnO Nanorod Arrays

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