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Nanoscale Analysis of a Hierarchical Hybrid Solar Cell in 3D.

Divitini G, Stenzel O, Ghadirzadeh A, Guarnera S, Russo V, Casari CS, Bassi AL, Petrozza A, Di Fonzo F, Schmidt V, Ducati C - Adv Funct Mater (2014)

Bottom Line: A cross section of the solar cell device is prepared by focused ion beam milling in a micropillar geometry, which allows a detailed 3D reconstruction of the titania photoanode by electron tomography.The 3D nanoparticle network is analyzed with tools from stochastic geometry to extract information related to the charge transport in the hierarchical solar cell.In particular, the experimental dataset allows direct visualization of the percolation pathways that contribute to the photocurrent.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science & Metallurgy, University of Cambridge 27 Charles Babbage Road, CB3 0FS, Cambridge, UK.

ABSTRACT

A quantitative method for the characterization of nanoscale 3D morphology is applied to the investigation of a hybrid solar cell based on a novel hierarchical nanostructured photoanode. A cross section of the solar cell device is prepared by focused ion beam milling in a micropillar geometry, which allows a detailed 3D reconstruction of the titania photoanode by electron tomography. It is found that the hierarchical titania nanostructure facilitates polymer infiltration, thus favoring intermixing of the two semiconducting phases, essential for charge separation. The 3D nanoparticle network is analyzed with tools from stochastic geometry to extract information related to the charge transport in the hierarchical solar cell. In particular, the experimental dataset allows direct visualization of the percolation pathways that contribute to the photocurrent.

No MeSH data available.


Related in: MedlinePlus

Map of the distance from the P3HT voxels to the titania in cross-section taken a) from the side and b) from the top. c) Subvolume considered for the distribution of the spherical distances between P3HT voxels and the nearest titania particle. d) Corresponding spherical contact distribution function D:[0,∞]→[0,1], where D(r) denotes the probability to reach the TiO2 phase from a random location in the pore phase. The exciton diffusion length in P3HT is roughly up to 8.5 nm.
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fig05: Map of the distance from the P3HT voxels to the titania in cross-section taken a) from the side and b) from the top. c) Subvolume considered for the distribution of the spherical distances between P3HT voxels and the nearest titania particle. d) Corresponding spherical contact distribution function D:[0,∞]→[0,1], where D(r) denotes the probability to reach the TiO2 phase from a random location in the pore phase. The exciton diffusion length in P3HT is roughly up to 8.5 nm.

Mentions: The properties of the pore space between the TiO2 particles can be analyzed to determine the possibility for charge injection into the semiconducting layer. In particular, in the 3D reconstruction it is possible to measure the distance between any point in the pores and the nearest TiO2 particle. In case of a perfect infiltration, in which P3HT entirely fills the pores in the TiO2 film, this corresponds to determining how much polymer is close enough to the P3HT/TiO2 interface to inject a photo-generated electron. To optimize the performance of the solar cell, this distance has to be smaller than, or at least comparable with, the exciton diffusion length in P3HT (values between 4 and 8.5 nm are found in literature.[28] We select a sub-volume (Figure 5c) of the TiO2 pillar to investigate this structural property. For our system, by considering spherical contact distances,[25] it is found that 75.8% of the pore space voxels are within 8.5 nm from the interface (Figure 5). A color-coded map of the distance between pore voxels and the TiO2 surface is reported in Figure 5, showing how the h-TiO2 morphology can interact with the polymer phase more effectively. This visualization is helpful in identifying the areas in the film where the intermixing between the two phases is not sufficient to generate free charges. We note that this type of information can only be retrieved from a 3D dataset with nanometer spatial resolution, such as electron tomography.


Nanoscale Analysis of a Hierarchical Hybrid Solar Cell in 3D.

Divitini G, Stenzel O, Ghadirzadeh A, Guarnera S, Russo V, Casari CS, Bassi AL, Petrozza A, Di Fonzo F, Schmidt V, Ducati C - Adv Funct Mater (2014)

Map of the distance from the P3HT voxels to the titania in cross-section taken a) from the side and b) from the top. c) Subvolume considered for the distribution of the spherical distances between P3HT voxels and the nearest titania particle. d) Corresponding spherical contact distribution function D:[0,∞]→[0,1], where D(r) denotes the probability to reach the TiO2 phase from a random location in the pore phase. The exciton diffusion length in P3HT is roughly up to 8.5 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376200&req=5

fig05: Map of the distance from the P3HT voxels to the titania in cross-section taken a) from the side and b) from the top. c) Subvolume considered for the distribution of the spherical distances between P3HT voxels and the nearest titania particle. d) Corresponding spherical contact distribution function D:[0,∞]→[0,1], where D(r) denotes the probability to reach the TiO2 phase from a random location in the pore phase. The exciton diffusion length in P3HT is roughly up to 8.5 nm.
Mentions: The properties of the pore space between the TiO2 particles can be analyzed to determine the possibility for charge injection into the semiconducting layer. In particular, in the 3D reconstruction it is possible to measure the distance between any point in the pores and the nearest TiO2 particle. In case of a perfect infiltration, in which P3HT entirely fills the pores in the TiO2 film, this corresponds to determining how much polymer is close enough to the P3HT/TiO2 interface to inject a photo-generated electron. To optimize the performance of the solar cell, this distance has to be smaller than, or at least comparable with, the exciton diffusion length in P3HT (values between 4 and 8.5 nm are found in literature.[28] We select a sub-volume (Figure 5c) of the TiO2 pillar to investigate this structural property. For our system, by considering spherical contact distances,[25] it is found that 75.8% of the pore space voxels are within 8.5 nm from the interface (Figure 5). A color-coded map of the distance between pore voxels and the TiO2 surface is reported in Figure 5, showing how the h-TiO2 morphology can interact with the polymer phase more effectively. This visualization is helpful in identifying the areas in the film where the intermixing between the two phases is not sufficient to generate free charges. We note that this type of information can only be retrieved from a 3D dataset with nanometer spatial resolution, such as electron tomography.

Bottom Line: A cross section of the solar cell device is prepared by focused ion beam milling in a micropillar geometry, which allows a detailed 3D reconstruction of the titania photoanode by electron tomography.The 3D nanoparticle network is analyzed with tools from stochastic geometry to extract information related to the charge transport in the hierarchical solar cell.In particular, the experimental dataset allows direct visualization of the percolation pathways that contribute to the photocurrent.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science & Metallurgy, University of Cambridge 27 Charles Babbage Road, CB3 0FS, Cambridge, UK.

ABSTRACT

A quantitative method for the characterization of nanoscale 3D morphology is applied to the investigation of a hybrid solar cell based on a novel hierarchical nanostructured photoanode. A cross section of the solar cell device is prepared by focused ion beam milling in a micropillar geometry, which allows a detailed 3D reconstruction of the titania photoanode by electron tomography. It is found that the hierarchical titania nanostructure facilitates polymer infiltration, thus favoring intermixing of the two semiconducting phases, essential for charge separation. The 3D nanoparticle network is analyzed with tools from stochastic geometry to extract information related to the charge transport in the hierarchical solar cell. In particular, the experimental dataset allows direct visualization of the percolation pathways that contribute to the photocurrent.

No MeSH data available.


Related in: MedlinePlus