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Polymer Photovoltaic Cells with Rhenium Oxide as Anode Interlayer.

Wei J, Bai D, Yang L - PLoS ONE (2015)

Bottom Line: It is found that insertion of ReO3 interfacial layer results in the decreased performance for P3HT: PCBM based solar cells.The results indicated the fact that a portion of ReO3 decomposed during thermal evaporation process, resulting in the formation of a buffer layer with a lower work function.As a consequence, a higher energy barrier was generated between the ITO and the active layer.

View Article: PubMed Central - PubMed

Affiliation: School of Management, Tianjin University of Technology, Tianjin, China.

ABSTRACT
The effect of a new transition metal oxide, rhenium oxide (ReO3), on the performance of polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend as buffer layer was investigated. The effect of the thickness of ReO3 layer on electrical characteristics of the polymer solar cells was studied. It is found that insertion of ReO3 interfacial layer results in the decreased performance for P3HT: PCBM based solar cells. In order to further explore the mechanism of the decreasing of the open-circuit voltage (Voc), the X-ray photoelectron spectroscopy (XPS) is used to investigate the ReO3 oxidation states. Kelvin Probe method showed that the work function of the ReO3 is estimated to be 5.13eV after thermal evaporation. The results indicated the fact that a portion of ReO3 decomposed during thermal evaporation process, resulting in the formation of a buffer layer with a lower work function. As a consequence, a higher energy barrier was generated between the ITO and the active layer.

No MeSH data available.


The O1s (a, b) and Re 4f (c, d) core-level spectra region and the peak fitting of the XPS spectra for ReO3 (b) and (c).
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pone.0133725.g004: The O1s (a, b) and Re 4f (c, d) core-level spectra region and the peak fitting of the XPS spectra for ReO3 (b) and (c).

Mentions: XPS measurement offers effective methods to study the electronic at the surface and interfaces of organic electronic devices. The possible decomposition mechanism was further explored by XPS. For simplicity, the original ReO3, ReO3 deposited on the ITO substrates by thermal evaporation and ReO3 remained in the quartz crucible are hereafter to as ReO3 (a), ReO3 (b), and ReO3 (c), respectively. Fig 4 shows the O1s and Re 4f core-level spectra region of the XPS spectra and XPS peak fitting of O1s and Re 4f for ReO3 (b) and ReO3 (c). The Re 4f core-level spectrum of the ReO3 (b) in Fig 4c shows a main peak at 44.4 eV. Two Re 4f shoulders peaks can be obviously observed at 42.3 eV and 46.8 eV, respectively. The Re 4f core-level spectrum of the ReO3 (c) in Fig 4d is located at 42.2 and 44.6 eV. More highly resolved (narrow) scans over the Re 4f 7/2, 5/2 spin-orbit coupling doublet peak (40–52 eV) regions were subsequently acquired. So de-convolution was carried out to deduce oxidation states of Re. De-convolution of the narrow scan profiles for the samples was done using the XPS PEAK program. Shirley (non-linear) baselines, 70% Gaussian/ 30% Lorentzian synthetic peaks were used and a set of constraining criteria applied to provide a measure of objectivity to the deconvolutions. A brief description of the criteria required is as follows: First, the peak areas of the synthetic Re 4f spin-orbit coupling doublets are constrained to be 1.33 (the ratio of the relative degeneracy given by 2J +1 of the 4f 7/2 and 4f 5/2 peaks (where J the spin orbit coupling constant = 7/2 and 5/2). Second, the spin-orbit coupling constants (i.e. the energy difference between the fitted spin orbit coupling doublet Re 4f peaks (ΔEB) are constrained to the literature value of 2.43 eV [13]. Third, the full width at half maximum (FWHM) of the synthetic peak doublets be limited to between 1 and 2 eV. The pick-fitting results in Fig 4c and 4d indicate that some of the ReO3 are transformed into ReO2 as indicated by the additional spectral line positioned at 42.3 eV and 44.7eV for Re 4f 7/2 and Re 4f 5/2, respectively. Spectral line at 44.4 eV and 46.8 eV is assigned to the Re 4f 7/2 and Re 4f 5/2 peaks of the ReO3 species, respectively. Although no obvious spectral line located at 46.4 eV and 48.8 eV for the existence of for Re7+ (Re2O7) was found in Fig 4c and 4d, we can see the existence of Re2O7 in Fig 4a and 4b of O1s core-level spectra and the peak fitting of the XPS spectra for ReO3 (b) and (c).


Polymer Photovoltaic Cells with Rhenium Oxide as Anode Interlayer.

Wei J, Bai D, Yang L - PLoS ONE (2015)

The O1s (a, b) and Re 4f (c, d) core-level spectra region and the peak fitting of the XPS spectra for ReO3 (b) and (c).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520519&req=5

pone.0133725.g004: The O1s (a, b) and Re 4f (c, d) core-level spectra region and the peak fitting of the XPS spectra for ReO3 (b) and (c).
Mentions: XPS measurement offers effective methods to study the electronic at the surface and interfaces of organic electronic devices. The possible decomposition mechanism was further explored by XPS. For simplicity, the original ReO3, ReO3 deposited on the ITO substrates by thermal evaporation and ReO3 remained in the quartz crucible are hereafter to as ReO3 (a), ReO3 (b), and ReO3 (c), respectively. Fig 4 shows the O1s and Re 4f core-level spectra region of the XPS spectra and XPS peak fitting of O1s and Re 4f for ReO3 (b) and ReO3 (c). The Re 4f core-level spectrum of the ReO3 (b) in Fig 4c shows a main peak at 44.4 eV. Two Re 4f shoulders peaks can be obviously observed at 42.3 eV and 46.8 eV, respectively. The Re 4f core-level spectrum of the ReO3 (c) in Fig 4d is located at 42.2 and 44.6 eV. More highly resolved (narrow) scans over the Re 4f 7/2, 5/2 spin-orbit coupling doublet peak (40–52 eV) regions were subsequently acquired. So de-convolution was carried out to deduce oxidation states of Re. De-convolution of the narrow scan profiles for the samples was done using the XPS PEAK program. Shirley (non-linear) baselines, 70% Gaussian/ 30% Lorentzian synthetic peaks were used and a set of constraining criteria applied to provide a measure of objectivity to the deconvolutions. A brief description of the criteria required is as follows: First, the peak areas of the synthetic Re 4f spin-orbit coupling doublets are constrained to be 1.33 (the ratio of the relative degeneracy given by 2J +1 of the 4f 7/2 and 4f 5/2 peaks (where J the spin orbit coupling constant = 7/2 and 5/2). Second, the spin-orbit coupling constants (i.e. the energy difference between the fitted spin orbit coupling doublet Re 4f peaks (ΔEB) are constrained to the literature value of 2.43 eV [13]. Third, the full width at half maximum (FWHM) of the synthetic peak doublets be limited to between 1 and 2 eV. The pick-fitting results in Fig 4c and 4d indicate that some of the ReO3 are transformed into ReO2 as indicated by the additional spectral line positioned at 42.3 eV and 44.7eV for Re 4f 7/2 and Re 4f 5/2, respectively. Spectral line at 44.4 eV and 46.8 eV is assigned to the Re 4f 7/2 and Re 4f 5/2 peaks of the ReO3 species, respectively. Although no obvious spectral line located at 46.4 eV and 48.8 eV for the existence of for Re7+ (Re2O7) was found in Fig 4c and 4d, we can see the existence of Re2O7 in Fig 4a and 4b of O1s core-level spectra and the peak fitting of the XPS spectra for ReO3 (b) and (c).

Bottom Line: It is found that insertion of ReO3 interfacial layer results in the decreased performance for P3HT: PCBM based solar cells.The results indicated the fact that a portion of ReO3 decomposed during thermal evaporation process, resulting in the formation of a buffer layer with a lower work function.As a consequence, a higher energy barrier was generated between the ITO and the active layer.

View Article: PubMed Central - PubMed

Affiliation: School of Management, Tianjin University of Technology, Tianjin, China.

ABSTRACT
The effect of a new transition metal oxide, rhenium oxide (ReO3), on the performance of polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend as buffer layer was investigated. The effect of the thickness of ReO3 layer on electrical characteristics of the polymer solar cells was studied. It is found that insertion of ReO3 interfacial layer results in the decreased performance for P3HT: PCBM based solar cells. In order to further explore the mechanism of the decreasing of the open-circuit voltage (Voc), the X-ray photoelectron spectroscopy (XPS) is used to investigate the ReO3 oxidation states. Kelvin Probe method showed that the work function of the ReO3 is estimated to be 5.13eV after thermal evaporation. The results indicated the fact that a portion of ReO3 decomposed during thermal evaporation process, resulting in the formation of a buffer layer with a lower work function. As a consequence, a higher energy barrier was generated between the ITO and the active layer.

No MeSH data available.