Photocarriers generation process and photovoltaic effect in PPHT thin film Schottky barrier devices

Sharma, Ganesh D.; Saxena, Dhiraj; Roy, M. S.

doi:10.1016/s0379-6779(99)00160-5

Cited by 11 publications

(4 citation statements)

References 12 publications

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“…At present, the use of thiophenes in different kinds of photoactive layers is being intensively studied. Bulk heterojunctions of thiophenes and fullerenes have been found to be promising candidates for application in solar energy devices. ,− In addition, junctions based on organized layers of thiophenes forming a heterojunction with organic − and inorganic − films have been investigated. Polythiophenes have certain advantages over PPVs, since thin films of substituted PTs are claimed to have self-organizing properties depending on the backbone substituents and the regioregularity. − Furthermore, the optical properties of PTs can be readily tailored via substitution on the main chain to obtain low-band-gap materials. , Another important property of PTs that makes them particularly suitable for solar cell applications is their enhanced photostability compared with that of PPVs.…”

Section: Introductionmentioning

confidence: 99%

Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO₂ Bilayers

et al. 2003

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The flash-photolysis time-resolved microwave conductivity technique (FP-TRMC) has been used to study photoinduced charge separation in bilayers consisting of a smooth, transparent, 80 nm thick layer of anatase TiO 2 onto which poly(3-hexylthiophene) (P3HT) sensitizer layers have been spin-coated. Interfacial charge separation, resulting from excitation of the polymer in the visible, is found to persist well into the millisecond time domain. Photoconductivity action spectra have been measured between 420 and 700 nm for P3HT layer thicknesses, L, from ∼2 to 200 nm. Using this electrodeless technique, the bilayers could be irradiated from either the polymer ("front") or semiconductor ("back") side. On front-side irradiation at 540 nm (close to the absorption maximum of the polymer), the efficiency of charge separation per incident photon (IPCSE) initially increased to a maximum value of 0.8% for L ≈ 10 nm. For thicker layers the IPCSE gradually decreased, eventually to 0.1% for L ≈ 170 nm. On back-side irradiation the IPCSE increased over the first 10 nm to a value close to the maximum found for front-side irradiation, and decreased only slightly for further increase in layer thickness. Analytical expressions for the thickness dependence based on exciton diffusion with a Lambert-Beer excitation profile have been used to fit the experimental data. Best fits were obtained for an exciton diffusion length, Λ () (Dτ) with D the diffusion coefficient and τ the natural lifetime), of 5.3 or 2.6 nm depending on whether excitons were taken to be reflected or quenched at the polymer/gas interface, respectively. The IPCSE decreased at high light intensities; an effect that is attributed to the occurrence of exciton-exciton annihilation within the polymer layer.

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Section: Introductionmentioning

confidence: 99%

Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO₂ Bilayers

et al. 2003

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“…Several authors have reported the observation of a slow transient response in organic photodiodes , , which is believed to be caused by the presence of electronic traps or defects in the organic semiconductor. The time constant for traps is typically in the range of a few ns for fast traps up to a few minutes for slow traps, depending on the energy level of traps in the material.…”

Section: Resultsmentioning

confidence: 99%

Achieving a Stable Time Response in Polymeric Radiation Sensors under Charge Injection by X-rays

Intaniwet

Mills

Sellin

et al. 2010

ACS Appl. Mater. Interfaces

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Existing inorganic materials for radiation sensors suffer from several drawbacks, including their inability to cover large curved areas, lack of tissue-equivalence, toxicity, and mechanical inflexibility. As an alternative to inorganics, poly(triarylamine) (PTAA) diodes have been evaluated for their suitability for detecting radiation via the direct creation of X-ray induced photocurrents. A single layer of PTAA is deposited on indium tin oxide (ITO) substrates, with top electrodes selected from Al, Au, Ni and Pd. The choice of metal electrode has a pronounced effect on the performance of the device; there is a direct correlation between the diode rectification factor and the metal-PTAA barrier height. A diode with an Al contact shows the highest quality of rectifying junction, and it produces a high X-ray photocurrent (several nA) that is stable during continuous exposure to 50 kV Mo Kα X-radiation over long timescales, combined with a high signal-to-noise ratio with fast response times of less than 0.25 s. Diodes with a low band-gap, 'Ohmic' contact, such as ITO/PTAA/Au, show a slow transient response. This result can be explained by the build-up of space charge at the metal-PTAA interface, caused by a high level of charge injection due to X-rayinduced carriers. These data provide new insights into the optimum selection of metals for Schottky contacts on organic materials, with wider applications in light sensors and photovoltaic devices.

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“…The resulting ZnO nano-particles are insoluble in pure methanol, but by addition of suitable amounts of less polar solvents such as dichloromethane, chloroform or chlorobenzene a stable solution is obtained. The poly-3-phenylhydrazone thiophene (PPHT) was synthesized by the simple condensation of thiophene-3 carboxyaldehyde with phenylhydrazine at low temperatures, i.e., 0-10 1C as reported by us [29]. The blends of PPHT and ZnO were prepared starting by dissolving PPHT in chlorobenzene.…”

Section: Experimental Detailmentioning

confidence: 99%

Photovoltaic devices based on PPHT: ZnO and dye-sensitized PPHT: ZnO thin films

Suresh

Balaraju

Sharma

et al. 2008

Solar Energy Materials and Solar Cells

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Photocarriers generation process and photovoltaic effect in PPHT thin film Schottky barrier devices

Cited by 11 publications

References 12 publications

Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO₂ Bilayers

Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO₂ Bilayers

Achieving a Stable Time Response in Polymeric Radiation Sensors under Charge Injection by X-rays

Photovoltaic devices based on PPHT: ZnO and dye-sensitized PPHT: ZnO thin films

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Photocarriers generation process and photovoltaic effect in PPHT thin film Schottky barrier devices

Cited by 11 publications

References 12 publications

Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO2 Bilayers

Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO2 Bilayers

Achieving a Stable Time Response in Polymeric Radiation Sensors under Charge Injection by X-rays

Photovoltaic devices based on PPHT: ZnO and dye-sensitized PPHT: ZnO thin films

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Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO₂ Bilayers

Contactless Determination of the Photoconductivity Action Spectrum, Exciton Diffusion Length, and Charge Separation Efficiency in Polythiophene-Sensitized TiO₂ Bilayers