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Polymer/Nanocrystal Hybrid Solar Cells: Influence of Molecular Precursor Design on Film Nanomorphology, Charge Generation and Device Performance.

MacLachlan AJ, Rath T, Cappel UB, Dowland SA, Amenitsch H, Knall AC, Buchmaier C, Trimmel G, Nelson J, Haque SA - Adv Funct Mater (2014)

Bottom Line: The formation of CdS domains is studied by simultaneous GIWAXS (grazing incidence wide-angle X-ray scattering) and GISAXS (grazing incidence small-angle X-ray scattering), revealing knowledge about crystal growth and the formation of different morphologies observed using TEM (transmission electron microscopy).These measurements show that there is a strong relationship between precursor structure and heterojunction nanomorphology.A combination of TAS (transient absorption spectroscopy) and photovoltaic device performance measurements is used to show the intricate balance required between charge photogeneration and percolated domains in order to effectively extract charges to maximize device power conversion efficiencies.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Centre for Plastic Electronics, Imperial College London Imperial College Road, London, SW7 2AZ, UK.

ABSTRACT

In this work, molecular tuning of metal xanthate precursors is shown to have a marked effect on the heterojunction morphology of hybrid poly(3-hexylthiophene-2,5-diyl) (P3HT)/CdS blends and, as a result, the photochemical processes and overall performance of in situ fabricated hybrid solar cells. A series of cadmium xanthate complexes is synthesized for use as in situ precursors to cadmium sulfide nanoparticles in hybrid P3HT/CdS solar cells. The formation of CdS domains is studied by simultaneous GIWAXS (grazing incidence wide-angle X-ray scattering) and GISAXS (grazing incidence small-angle X-ray scattering), revealing knowledge about crystal growth and the formation of different morphologies observed using TEM (transmission electron microscopy). These measurements show that there is a strong relationship between precursor structure and heterojunction nanomorphology. A combination of TAS (transient absorption spectroscopy) and photovoltaic device performance measurements is used to show the intricate balance required between charge photogeneration and percolated domains in order to effectively extract charges to maximize device power conversion efficiencies. This study presents a strong case for xanthate complexes as a useful route to designing optimal heterojunction morphologies for use in the emerging field of hybrid organic/inorganic solar cells, due to the fact that the nanomorphology can be tuned via careful design of these precursor materials.

No MeSH data available.


Related in: MedlinePlus

Bright field TEM (transmission electron microscopy) images of thin films of hybrid P3HT/CdS heterojunctions, fabricated from a series of Cd-xanthate precursors with increasing ligand moieties from left to right. The darker regions of contrast are indicative of a higher concentration of cadmium.
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fig02: Bright field TEM (transmission electron microscopy) images of thin films of hybrid P3HT/CdS heterojunctions, fabricated from a series of Cd-xanthate precursors with increasing ligand moieties from left to right. The darker regions of contrast are indicative of a higher concentration of cadmium.

Mentions: The morphology of in situ formed P3HT/CdS hybrid blend thin films was first studied using bright field TEM, typical images of which can be seen in Figure2. From left to right the images show films fabricated using a xanthate precursor of increasing ligand moiety size, from ethyl through to heptyl. It is apparent that as the ligand moiety is changed the morphology of the blends changes, with the domain sizes within the films becoming smaller as a larger ligand is used. Upon close inspection of the TEM image of the heptyl sample (Figure 2, Heptyl), discrete particles can be seen. These particles, although still observable, become less easy to isolate visually when moving towards a smaller ligand moiety on the left hand side of the figure. It appears that an increase of the alkyl chain size of the precursors results in a reduction in the aggregation of the cadmium sulfide nanoparticles upon decomposition of the xanthate precursors. It is worth noting however that the TEM images only provide a top-down look at the morphology and although we can see a trend in this direction we can only assume that the landscape looks similar in the z-direction as well. The significantly different morphologies of the P3HT/CdS hybrid films as shown in the TEM images in Figure 2 support our hypothesis that molecular precursor design is a valuable tool for tuning the nanomorphology of in situ prepared polymer/nanocrystal absorber layers towards efficient charge generation and transport. However, target-oriented molecular design of the precursors requires knowledge of the processes going on during the in situ formation of these films.


Polymer/Nanocrystal Hybrid Solar Cells: Influence of Molecular Precursor Design on Film Nanomorphology, Charge Generation and Device Performance.

MacLachlan AJ, Rath T, Cappel UB, Dowland SA, Amenitsch H, Knall AC, Buchmaier C, Trimmel G, Nelson J, Haque SA - Adv Funct Mater (2014)

Bright field TEM (transmission electron microscopy) images of thin films of hybrid P3HT/CdS heterojunctions, fabricated from a series of Cd-xanthate precursors with increasing ligand moieties from left to right. The darker regions of contrast are indicative of a higher concentration of cadmium.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384757&req=5

fig02: Bright field TEM (transmission electron microscopy) images of thin films of hybrid P3HT/CdS heterojunctions, fabricated from a series of Cd-xanthate precursors with increasing ligand moieties from left to right. The darker regions of contrast are indicative of a higher concentration of cadmium.
Mentions: The morphology of in situ formed P3HT/CdS hybrid blend thin films was first studied using bright field TEM, typical images of which can be seen in Figure2. From left to right the images show films fabricated using a xanthate precursor of increasing ligand moiety size, from ethyl through to heptyl. It is apparent that as the ligand moiety is changed the morphology of the blends changes, with the domain sizes within the films becoming smaller as a larger ligand is used. Upon close inspection of the TEM image of the heptyl sample (Figure 2, Heptyl), discrete particles can be seen. These particles, although still observable, become less easy to isolate visually when moving towards a smaller ligand moiety on the left hand side of the figure. It appears that an increase of the alkyl chain size of the precursors results in a reduction in the aggregation of the cadmium sulfide nanoparticles upon decomposition of the xanthate precursors. It is worth noting however that the TEM images only provide a top-down look at the morphology and although we can see a trend in this direction we can only assume that the landscape looks similar in the z-direction as well. The significantly different morphologies of the P3HT/CdS hybrid films as shown in the TEM images in Figure 2 support our hypothesis that molecular precursor design is a valuable tool for tuning the nanomorphology of in situ prepared polymer/nanocrystal absorber layers towards efficient charge generation and transport. However, target-oriented molecular design of the precursors requires knowledge of the processes going on during the in situ formation of these films.

Bottom Line: The formation of CdS domains is studied by simultaneous GIWAXS (grazing incidence wide-angle X-ray scattering) and GISAXS (grazing incidence small-angle X-ray scattering), revealing knowledge about crystal growth and the formation of different morphologies observed using TEM (transmission electron microscopy).These measurements show that there is a strong relationship between precursor structure and heterojunction nanomorphology.A combination of TAS (transient absorption spectroscopy) and photovoltaic device performance measurements is used to show the intricate balance required between charge photogeneration and percolated domains in order to effectively extract charges to maximize device power conversion efficiencies.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Centre for Plastic Electronics, Imperial College London Imperial College Road, London, SW7 2AZ, UK.

ABSTRACT

In this work, molecular tuning of metal xanthate precursors is shown to have a marked effect on the heterojunction morphology of hybrid poly(3-hexylthiophene-2,5-diyl) (P3HT)/CdS blends and, as a result, the photochemical processes and overall performance of in situ fabricated hybrid solar cells. A series of cadmium xanthate complexes is synthesized for use as in situ precursors to cadmium sulfide nanoparticles in hybrid P3HT/CdS solar cells. The formation of CdS domains is studied by simultaneous GIWAXS (grazing incidence wide-angle X-ray scattering) and GISAXS (grazing incidence small-angle X-ray scattering), revealing knowledge about crystal growth and the formation of different morphologies observed using TEM (transmission electron microscopy). These measurements show that there is a strong relationship between precursor structure and heterojunction nanomorphology. A combination of TAS (transient absorption spectroscopy) and photovoltaic device performance measurements is used to show the intricate balance required between charge photogeneration and percolated domains in order to effectively extract charges to maximize device power conversion efficiencies. This study presents a strong case for xanthate complexes as a useful route to designing optimal heterojunction morphologies for use in the emerging field of hybrid organic/inorganic solar cells, due to the fact that the nanomorphology can be tuned via careful design of these precursor materials.

No MeSH data available.


Related in: MedlinePlus