Savita P. Somani

Toward organic thick film solar cells: Three dimensional bulk heterojunction organic thick film solar cell using fullerene single crystal nanorods

Fullerene single crystal nanorods (C60-nanorods) are synthesized by simple liquid/liquid interface precipitation method. Three dimensional bulk heterojunction donor-acceptor-type organic thick film solar cell is demonstrated having an active layer made from C60-nanorods and regioregular poly(3-octylthiophene). C60-nanorods seem to be promising material for organic solar cell applications. Our preliminary results opens an area of “organic thick film solar cells” which was almost thought to be impossible due to lower mobility of charge carriers and small exciton diffusion lengths in most of the organic materials, including small molecules and conjugated polymers.

Application of metal nanoparticles decorated carbon nanotubes in photovoltaics

Carbon nanotubes decorated with metal nanoparticles are introduced to photovoltaic application. The introduction of metal nanoparticles in the organic/organic-inorganic heterojunction solar cells is expected to improve the exciton dissociation (due to strong electric field at the metal-organics interface) and hence photovoltaic action. An improved photovoltaic action is indeed observed in n-Si/poly(3-octylthiophene) heterojunction solar cells incorporating multiwalled carbon nanotubes (MWCN) decorated with platinum metal nanoparticles (Pt: 20wt%, 10–15nm) as compared to pristine MWCN. The incorporation of metal nanoparticles should provide an alternative strategy to improve the photovoltaic performance of organic/organic-inorganic solar cells.

Improving photovoltaic response of poly„3-hexylthiophene…/n-Si heterojunction by incorporating double walled carbon nanotubes

Poly(3-hexylthiophene)/n-Si heterojunction solar cells were studied with and without incorporation of double walled carbon nanotubes (DWCNs) in the polymer layer. Performance of the device improves by manyfold by incorporation of DWCN. The authors report power conversion efficiency, open circuit voltage, short-circuit current density, and fill factor of 0.026%, 0.446V, 0.3398mA∕cm2, and 0.17, respectively, for an unoptimized cell containing DWCN. Reference cells without DWCNs show much lower performance. DWCN incorporation yields better hole transport, easy exciton splitting, and suppression of charge recombination, thereby improving photovoltaic action. DWCN seems promising materials for improving hole transport in organic solar cells.

Improving the photovoltaic response of a poly(3-octylthiophene)/n-Si heterojunction by incorporating double-walled carbon nanotubes

Poly(3-octylthiophene)/n-Si heterojunction solar cells were studied with and without incorporation of double-walled carbon nanotubes (DWCNs) in the polymer layer. The performance of the device improves significantly by the incorporation of DWCNs. We report a power conversion efficiency, open circuit voltage, short-circuit current density and fill factor of 0.49%, 0.53 V, 5.9 mA cm−2 and 0.15 respectively for an un-optimized cell containing DWCNs. Reference cells without DWCNs show a much lower performance. DWCN incorporation yields better hole transport, easy exciton splitting and suppression of charge recombination, thereby improving photovoltaic action. DWCN seems a promising material for improving hole transport in organic solar cells.

Double-Walled Carbon Nanotubes-Incorporated Donor–Acceptor-Type Organic Photovoltaic Devices Using Poly(3-octylthiophene) and C60

Donor–acceptor-type photovoltaic devices with a heterojunction between regioregular poly(3-octylthiophene) (P3OT) and C60 are fabricated with and without the addition of double-walled carbon nanotubes (DWCNs) in the polymer layer. Incorporation of DWCNs in the polymer layer improves the performance of the device by many folds, which is attributable to improved exciton dissociation and better charge transport leading to the suppression of charge carrier recombination. We report an open-circuit voltage, short-circuit current density, fill factor and conversion efficiency (%) of approximately 0.37 V, 0.014 mA/cm2, 0.22 and 0.001%, respectively, for an unoptimized device incorporating DWCNs.

Concept and demonstration of all organic Gratzel solar cell (dye sensitized solar cell)

The authors present the concept of “all organic Gratzel/dye sensitized solar cell” and demonstrate such a device using high Tauc band gap (above 2.5eV) amorphous carbon thin films doped with nitrogen (n type) deposited by microwave assisted surface wave plasma chemical vapor deposition and sensitized with copper-phthalocyanine thin films. Open circuit voltage and short circuit current density obtained are about 0.53V (versus Ag∕AgCl, reference electrode) and 8.52×10−6A∕cm2, respectively. The mechanism of photovoltaic action in such cells may be similar to dye sensitized photoelectrochemical cells using nano-TiO2∕ZnO porous thick films.