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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 molecular structure of the materials used in the experiment and the device structure.
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pone.0133725.g001: The molecular structure of the materials used in the experiment and the device structure.

Mentions: The procedure for the solar cell device fabrication is described as follows. The patterned ITO-coated glass was ultra-sonicated with acetone, isopropanol, and de-ionized water for 10 min. The PEDOT: PSS layer of about 25 nm thickness was obtained by spin coating at 3000 rpm for 40 s from an aqueous solution (Baytron P VP Al 4083) on ITO coated glass substrates, followed by baking at 120°C for 5 minutes in air. ReO3 (Aldrich, purity 99.9%) was thermally evaporated onto PEDOT:PSS in 0.2, 0.5, 1, and 3 nm thick under a vacuum of about 1×10−6 Torr. The blend of P3HT: PCBM (1:0.8 weight-ratio) chlorobenzene solution was spin coated at 1000 rpm for 60 s. The P3HT: PCBM coated substrates were heated at 150°C in a nitrogen atmosphere for 10 min to remove residual solvent before transferring to a vacuum system. Finally, 100nm thickness Al was thermally deposited on top of the active layer under a vacuum of about 1×10−6 Torr. A control device using PEDOT: PSS as anode buffer layer is also fabricated for comparsion. The active layer area of the device was 0.09 cm2. The un-encapsulated devices were measured in the ambient atmosphere (25±5°C, 35±5% relative humidity) under intensity of 100 mW/cm2 white light illuminations by using a 300 W solar simulator (Thermal Oriel 91160) with an AM1.5 G filter. The light intensity was calibrated with an Oriel mono-Si reference cell (CROWNTECH PVM 272 certificated by NREL). I-V curves were swept with a Keithley 2400 source meter from -1 to +1 V in steps of 10 mV with a speed of 0.1 s per step until stable efficiency. The WF of the ITO substrate coated with ReO3 interlayer was evaluated by Kelvin probe method in the air using a KP 020 Ambient Kelvin Probe system. The XPS spectra was recorded using a Kratos Axis Ultra DLD spectrometer employing a monochromated Al-Kα X-ray source (hv = 1486.6 eV), hybrid (magnetic / electrostatic) optics and a multi-channel plate and delay line detector (DLD). All XPS spectra were recorded using an aperture slot of 300 * 700 microns. Survey spectra were recorded with a pass energy of 160 eV, and high resolution spectra with a pass energy of 40 eV. In both wide and narrow scans, the C1s peak at 285.0 eV of adventitious surface hydrocarbons was used to reference charge-induced binding energy shifts in the sample. The molecular structure of the materials used in the experiment and the schematic device structure are shown in Fig 1.


Polymer Photovoltaic Cells with Rhenium Oxide as Anode Interlayer.

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

The molecular structure of the materials used in the experiment and the device structure.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0133725.g001: The molecular structure of the materials used in the experiment and the device structure.
Mentions: The procedure for the solar cell device fabrication is described as follows. The patterned ITO-coated glass was ultra-sonicated with acetone, isopropanol, and de-ionized water for 10 min. The PEDOT: PSS layer of about 25 nm thickness was obtained by spin coating at 3000 rpm for 40 s from an aqueous solution (Baytron P VP Al 4083) on ITO coated glass substrates, followed by baking at 120°C for 5 minutes in air. ReO3 (Aldrich, purity 99.9%) was thermally evaporated onto PEDOT:PSS in 0.2, 0.5, 1, and 3 nm thick under a vacuum of about 1×10−6 Torr. The blend of P3HT: PCBM (1:0.8 weight-ratio) chlorobenzene solution was spin coated at 1000 rpm for 60 s. The P3HT: PCBM coated substrates were heated at 150°C in a nitrogen atmosphere for 10 min to remove residual solvent before transferring to a vacuum system. Finally, 100nm thickness Al was thermally deposited on top of the active layer under a vacuum of about 1×10−6 Torr. A control device using PEDOT: PSS as anode buffer layer is also fabricated for comparsion. The active layer area of the device was 0.09 cm2. The un-encapsulated devices were measured in the ambient atmosphere (25±5°C, 35±5% relative humidity) under intensity of 100 mW/cm2 white light illuminations by using a 300 W solar simulator (Thermal Oriel 91160) with an AM1.5 G filter. The light intensity was calibrated with an Oriel mono-Si reference cell (CROWNTECH PVM 272 certificated by NREL). I-V curves were swept with a Keithley 2400 source meter from -1 to +1 V in steps of 10 mV with a speed of 0.1 s per step until stable efficiency. The WF of the ITO substrate coated with ReO3 interlayer was evaluated by Kelvin probe method in the air using a KP 020 Ambient Kelvin Probe system. The XPS spectra was recorded using a Kratos Axis Ultra DLD spectrometer employing a monochromated Al-Kα X-ray source (hv = 1486.6 eV), hybrid (magnetic / electrostatic) optics and a multi-channel plate and delay line detector (DLD). All XPS spectra were recorded using an aperture slot of 300 * 700 microns. Survey spectra were recorded with a pass energy of 160 eV, and high resolution spectra with a pass energy of 40 eV. In both wide and narrow scans, the C1s peak at 285.0 eV of adventitious surface hydrocarbons was used to reference charge-induced binding energy shifts in the sample. The molecular structure of the materials used in the experiment and the schematic device structure are shown in Fig 1.

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.