Solar to electric energy conversion device

Abstract

The present invention features a solar-to-electric energy conversion device based on a light absorbing electrode coupled to a one-dimensional nanoparticle based photonic crystal. The function of the latter is to localize the incident light within the electrode thus enhancing the optical absorption and the power conversion efficiency of the so called dye-sensitized and organic (polymer based or hybrids) cell. The photonic crystal comprises alternating layers possessing different index of refraction and can be easily integrated into the cell.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a solar-to-electric energy conversion device having a light absorbing electrode coupled to a porous photonic crystal or multilayer Bragg reflector. The porous reflecting element is used to enhance the power conversion efficiency of the solar cell device by selectively increasing the optical absorption in the electrode.BACKGROUND OF THE INVENTION

[0002] The research on different solar-to-electric energy conversion devices made of materials alternative to silicon has been boosted in recent years for a number of reasons such as the search for lower cost processes or added value features, such as transparency. Among them, one of the devices that have shown higher efficiency is dye-sensitized solar cells (DSSC), also known as Grätzel cells, U.S. Pat. No. 5,084,365. The DSSC combine a solid wide band gap semiconductor with a liquid ionic conductor. The former usually consists of one electrode made of a layer of a few micrometers o...

Examples

example 1

Fabrication of the Dye-Sensitized Solar Cell 1

[0082]Dye-Sensitized Solar Cell Coupled to a 1-Dimensional Photonic Crystal with Lattice Parameter of 180±10 nm (95±5 nm SiO2-85±5 nm nc-TiO2) Presenting its Reflectance Maximum at 600 nm

[0083]A 350 nm thick transparent titanium dioxide electrode is deposited by doctor-blading onto a previously cleaned 25 mm×25 mm conducting substrate (fluorine-doped SnO2 conducting glass, Hartford Glass). The anatase particle paste the electrodes are made of was purchased from Solaronix (Ti-Nanoxide HT, Solaronix). The TiO2 layer coated glass so prepared is heated to 450° C. during 30 minutes under oxygen for sintering. On the other hand, nanocrystalline TiO2 particles are synthesised by using a procedure reported by Burnside et al, based on the hydrolysis of titanium isopropoxide followed by a peptization process under hydrothermal conditions. In our case, 20 ml of titanium isopropoxide (97% Aldrich) are added to 36 ml of Milli-Q water and stirred for ...

example 2

Fabrication of the Dye-Sensitized Solar Cell 2

[0084]Dye-Sensitized Solar Cell Coupled to a 1-Dimensional Photonic Crystal with Lattice Parameter of 140±10 nm (55±5 nm SiO2-85±5 nm nc-TiO2) Presenting its Reflectance Maximum at 450 nm

[0085]The same fabrication procedure mentioned in Example 1 is employed to build the dye-sensitized solar cell 2. In this case, the six layer periodic stack is made from silica (2 wt. % precursor solution) and titania (5 wt. % precursor solution) nanoparticles. The precursor suspensions for the spin-coating process are obtained by suspending TiO2 or SiO2 nanoparticles in a mixture of water (21 vol. %) and methanol (79 vol. %), and the rotation speed is kept at 100 rps during the spin-coating process. The IV curve corresponding to this dye-sensitized solar cell is presented in FIG. 3 (blue squares). The IV curve corresponding to a reference dye-sensitized solar cell is also shown in this graph (black circles). For this comparison, the same electrode thick...

example 3

Fabrication of the Dye-Sensitized Solar Cell

[0086]Dye-Sensitized Solar Cell Coupled to a 1-Dimensional Photonic Crystal with Lattice Parameter of 195±15 nm (110±10 nm SiO2-85±5 nm nc-TiO2) Presenting its Reflectance Maximum at 520 nm

[0087]The same fabrication procedure mentioned in Example 1 is employed to build the dye-sensitized solar cell 3. In this case, the six layer periodic stack is made from silica (3 wt. % precursor solution) and titania (5 wt. % precursor solution) nanoparticles. The precursor suspensions for the spin-coating process are obtained by suspending TiO2 or SiO2 nanoparticles in a mixture of water (21 vol. %) and methanol (79 vol. %), and the rotation speed is kept at 100 rps during the spin-coating process. The IV curve and the specular reflectance spectrum corresponding to this dye-sensitized solar cell are presented in FIG. 6a (circles) and 6b, respectively. In FIG. 6b is also plotted the absorption spectrum of the ruthenium based dye (black solid line, in ar...

FIELD OF THE INVENTION

[0001] The present invention relates to a solar-to-electric energy conversion device having a light absorbing electrode coupled to a porous photonic crystal or multilayer Bragg reflector. The porous reflecting element is used to enhance the power conversion efficiency of the solar cell device by selectively increasing the optical absorption in the electrode.BACKGROUND OF THE INVENTION

[0002] The research on different solar-to-electric energy conversion devices made of materials alternative to silicon has been boosted in recent years for a number of reasons such as the search for lower cost processes or added value features, such as transparency. Among them, one of the devices that have shown higher efficiency is dye-sensitized solar cells (DSSC), also known as Grätzel cells, U.S. Pat. No. 5,084,365. The DSSC combine a solid wide band gap semiconductor with a liquid ionic conductor. The former usually consists of one electrode made of a layer of a few micrometers o...

Examples

example 1

Fabrication of the Dye-Sensitized Solar Cell 1

[0082]Dye-Sensitized Solar Cell Coupled to a 1-Dimensional Photonic Crystal with Lattice Parameter of 180±10 nm (95±5 nm SiO2-85±5 nm nc-TiO2) Presenting its Reflectance Maximum at 600 nm

[0083]A 350 nm thick transparent titanium dioxide electrode is deposited by doctor-blading onto a previously cleaned 25 mm×25 mm conducting substrate (fluorine-doped SnO2 conducting glass, Hartford Glass). The anatase particle paste the electrodes are made of was purchased from Solaronix (Ti-Nanoxide HT, Solaronix). The TiO2 layer coated glass so prepared is heated to 450° C. during 30 minutes under oxygen for sintering. On the other hand, nanocrystalline TiO2 particles are synthesised by using a procedure reported by Burnside et al, based on the hydrolysis of titanium isopropoxide followed by a peptization process under hydrothermal conditions. In our case, 20 ml of titanium isopropoxide (97% Aldrich) are added to 36 ml of Milli-Q water and stirred for ...

example 2

Fabrication of the Dye-Sensitized Solar Cell 2

[0084]Dye-Sensitized Solar Cell Coupled to a 1-Dimensional Photonic Crystal with Lattice Parameter of 140±10 nm (55±5 nm SiO2-85±5 nm nc-TiO2) Presenting its Reflectance Maximum at 450 nm

[0085]The same fabrication procedure mentioned in Example 1 is employed to build the dye-sensitized solar cell 2. In this case, the six layer periodic stack is made from silica (2 wt. % precursor solution) and titania (5 wt. % precursor solution) nanoparticles. The precursor suspensions for the spin-coating process are obtained by suspending TiO2 or SiO2 nanoparticles in a mixture of water (21 vol. %) and methanol (79 vol. %), and the rotation speed is kept at 100 rps during the spin-coating process. The IV curve corresponding to this dye-sensitized solar cell is presented in FIG. 3 (blue squares). The IV curve corresponding to a reference dye-sensitized solar cell is also shown in this graph (black circles). For this comparison, the same electrode thick...

example 3

Fabrication of the Dye-Sensitized Solar Cell

[0086]Dye-Sensitized Solar Cell Coupled to a 1-Dimensional Photonic Crystal with Lattice Parameter of 195±15 nm (110±10 nm SiO2-85±5 nm nc-TiO2) Presenting its Reflectance Maximum at 520 nm

[0087]The same fabrication procedure mentioned in Example 1 is employed to build the dye-sensitized solar cell 3. In this case, the six layer periodic stack is made from silica (3 wt. % precursor solution) and titania (5 wt. % precursor solution) nanoparticles. The precursor suspensions for the spin-coating process are obtained by suspending TiO2 or SiO2 nanoparticles in a mixture of water (21 vol. %) and methanol (79 vol. %), and the rotation speed is kept at 100 rps during the spin-coating process. The IV curve and the specular reflectance spectrum corresponding to this dye-sensitized solar cell are presented in FIG. 6a (circles) and 6b, respectively. In FIG. 6b is also plotted the absorption spectrum of the ruthenium based dye (black solid line, in ar...

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