Photoconducting nanocrystalline lead sulphide thin films obtained by chemical bath deposition

Tin Sulphide is a layered compound which retains its structure when deposited as thin films by thermal evaporation. The films were found to have oriented growth with the direction of orientation changing with film thickness. The film's morphology was found to change with orientation. The poor conductivity of the thicker samples made it difficult to make photocunductivity characterisation. However, unlike reported the thinner samples showed photo-sensitivity to be independent of film thickness and grain size with a high presistent photocurrent. With their absorption, photosensitivty, optimum band-gap and traps within the bandgap giving the charge carriers a longer life-time, thin samples of tin sulphide gives adequate scope designing efficient photovoltaics. The refractive index was modeled using Sellmeir's model, while most of the previous studies talk of Wemple-DiDomenico single oscillator model or Cauchy's dispersion relation. The Sellmeir's fitting parameters are reported which can be of use in ellipsometric studies.

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“…"Sensitivity" (S) is usually used as a figure of merit while discussing the photoconductivity of films and is given as [34]- [37] …”

Section: Photoconductivitymentioning

confidence: 99%

Suitability of SnS thin films for photovoltaic application due to the existence of persistent photocurrent

Gupta

Arun

2015

Physica Status Solidi (b)

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“…Methods such as drop casting, spin coating, and dip coating of colloidal nanocrystals are extensively and mostly used for the fabrication of devices, as reported in literature [ 9 , 10 , 11 ]. Regardless of the solution processing deposition method, the fabrication of compact and homogeneous QD solids with controlled thickness and low structural-defect concentration was addressed to develop high-efficiency photodetector devices [ 6 , 12 , 13 ]. Alongside the QD-solid fabrication technique, significant work was devoted to the study of the chemical composition of nanocrystal dispersion since it was shown to be a crucial factor in the optimization of charge-carrier dynamics in the QD solid [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Charge Transport in Trap-Sensitized Infrared PbS Quantum-Dot-Based Photoconductors: Pros and Cons

et al. 2018

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Control of quantum-dot (QD) surface chemistry offers a direct approach for the tuning of charge-carrier dynamics in photoconductors based on strongly coupled QD solids. We investigate the effects of altering the surface chemistry of PbS QDs in such QD solids via ligand exchange using 3-mercaptopropionic acid (MPA) and tetrabutylammonium iodide (TBAI). The roll-to-roll compatible doctor-blade technique was used for the fabrication of the QD solid films as the photoactive component in photoconductors and field-effect phototransistors. The ligand exchange of the QD solid film with MPA yields superior device performance with higher photosensitivity and detectivity, which is due to less dark current and lower noise level as compared to ligand exchange with TBAI. In both cases, the mechanism responsible for photoconductivity is related to trap sensitization of the QD solid, in which traps are responsible of high photoconductive gain values, but slow response times under very low incident optical power (<1 pW). At medium–high incident optical powers (>100 pW), where traps are filled, both MPA- and TBAI-treated photodevices exhibit similar behavior, characterized by lower responsivity and faster response time, as limited by the mobility in the QD solid.

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“…The estimated band gap for the FeS 2 thin film is 1.75 eV. This significant blue shift (0.85 eV) of the band gap from the bulk value of 0.95 eV, could be attributed to quantum size effect induced by the Nano crystallites in the film[17] [18].…”

mentioning

confidence: 93%

Growth of a Pure and Single Phase Iron Sulfide (Pyrite) Thin Film by Electrochemical Deposition for Photovoltaic Applications

Botchway¹,

Ampong²,

Nkrumah³

et al. 2019

OJAppS

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Single phase iron pyrite (FeS 2) films have been successfully deposited on ITO-coated glass substrates using a 3-electrode electrochemical system with graphite as the counter electrode and Ag/AgCl as the reference electrode. In this single-step electrodeposition, the FeS precursor thin film was directly electrodeposited on the conductive substrate from the electrolytic bath solution which contained FeSO 4 •7H 2 O as an iron source, and Na 2 S 2 O 3 •5H 2 O as a sulfur source. The deposition was carried out potentiostatically at a constant potential of −0.9 V vs. Ag/AgCl at room temperature. The growth of the iron pyrite phase was achieved by annealing the as-deposited at 500˚C for an hour in an ambient of sulfur to form the pyrite phase. For sulfurization, two different techniques, one using the Kipp's apparatus and a second, which involved heating elemental sulfur at 200˚C, were used for the production of the sulfur gas. X-ray diffraction analyses of the sulfurized films showed that both sulfurization techniques appeared to form the pyrite phase, however, the second method yielded films with maximum crystalline order and stoichiometry with no discernable impurity peaks. Optical absorption measurements revealed the existence of a direct transition with an estimated band gap of 1.75 eV. SEM micrograph showed a compact morphology with a rough surface made up of crystallites of irregular shapes and sizes with well-defined edges, covering the entire substrate. EDAX analysis of the film was consistent with the formation of FeS 2 pyrite thin films.

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Photoconducting nanocrystalline lead sulphide thin films obtained by chemical bath deposition

Cited by 42 publications

References 23 publications

Suitability of SnS thin films for photovoltaic application due to the existence of persistent photocurrent

Suitability of SnS thin films for photovoltaic application due to the existence of persistent photocurrent

Charge Transport in Trap-Sensitized Infrared PbS Quantum-Dot-Based Photoconductors: Pros and Cons

Growth of a Pure and Single Phase Iron Sulfide (Pyrite) Thin Film by Electrochemical Deposition for Photovoltaic Applications

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