The influence of wrinkled ZnO on inverted low bandgap thin film solar cells

Chen, Chao-Shuo; Yang, Po-Chun; Shen, Yuning; Ma, Shou-Yuan; Shiu, Shu-Chia; Hung, Shih-Che; Lin, Shang-Hong; Lin, Ching-Fuh

doi:10.1016/j.solmat.2012.01.042

Cited by 14 publications

(16 citation statements)

References 29 publications

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“…(a) Ramping rate with respect to time of static annealing (SA) process for the ZnO layers annealed at 100 °C, 150 °C, 170 °C, and 200 °C. (b) The correlation among the concentration of solution, annealing temperature and heating rate was shown in the map by the analysis between our work and previous ones. − (c) Comparison of heating mechanics between dynamic annealing (DA) and static annealing (SA).…”

Section: Resultsmentioning

confidence: 56%

“…24 ZnO waves were prepared by spin coating of a sol−gel on ITO followed by annealing at 200 °C for 30 min in an oven after SA with an unknown ramping rate 24−30 for a 0.5 M ZnO solution. 25 ZnO ripples were prepared by depositing a sol−gel solution and heating the layer to 375 °C after DA with a ramping rate of 22 °C/min for a 0.75 M solution. 26 All of these studies used DA processes and high temperatures (over 200 °C) to achieve the wrinkle structures, except the SA process by Chen.…”

Section: Introductionmentioning

confidence: 99%

“…26 All of these studies used DA processes and high temperatures (over 200 °C) to achieve the wrinkle structures, except the SA process by Chen. et al 25 To date, a comparison of the efficiencies of solar cells made using wrinkled or flat ZnO structures has rarely been conducted. However, Yu 27 et al compared ZnO thin films and the device performance of IPSCs with an active layer of poly thieno[3,4-b]thiophene/benzodithiophene (PTB7-F20):[6,6]-phenyl C71-butyric acid methyl ester (PC 71 BM) BHJ produced using either SA and DA with an unknown ramping rate and a final annealing at 200 °C for 1 h in 0.44 and 0.54 M solutions.…”

Section: Introductionmentioning

confidence: 99%

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Effects of the Wrinkle Structure and Flat Structure Formed During Static Low-Temperature Annealing of ZnO on the Performance of Inverted Polymer Solar Cells

et al. 2017

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Low-temperature annealing of Zinc oxide (ZnO) films as electron transport layers for inverted polymer solar cells was investigated. A wrinkled morphology of the ZnO film has previously been mostly observed after dynamic annealing (DA). In this study, we investigated the effect of static annealing (SA) of ZnO layers deposited by the sol−gel method at 25 °C, 150 °C, and 200 °C for 10 min in air. We observed the formation of the wrinkle structures on the surface of the ZnO sample annealed at 150 °C, while flat structures were formed at 200 °C. Here, a variable ramping/heating rate provided by a static annealing process resulted in a variable solvent evaporation rate and transformation of the precursor. The tensile stresses induced by slower heating (∼40 °C/min in a 0.75 M ZnO solution) and residual solvent resulted in an amorphous layer with a wrinkled structure at a low temperature of 150 °C. A flat structure was obtained with slightly different dynamics at a faster heating rate (∼56 °C/min) at 200 °C. Consequently, the SA process enabled us to fabricate the desired wrinkled morphology at lower annealing temperatures (e.g., 150 °C) than ever reported for DA processes; the ramp rate in the 200 °C SA process was too high to form the wrinkled structure. The short circuit current of the device using a wrinkle structure was better than that of the device with flat structure due to optical effects of internal reflection, scattering and light-trapping by wrinkles, while the transmittance and fill factor of the device using a flat ZnO layer annealed at 200 °C was better than those of the device with a ZnO layer annealed at 150 °C. This was due to better film quality from the higher processing temperature, a low surface roughness, and less defects. However, the power conversion efficiency of devices with both films was similar, meaning that the low temperature annealing process producing the wrinkle structure can be used for fabricating devices with polymer substrates and gas barriers for flexible electronics. In the case of the wrinkled structure, we observed that the wrinkle height was highly dependent on the ramping rate, ZnO solution concentration, and annealing temperature, compared with previous works.

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Section: Resultsmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of the Wrinkle Structure and Flat Structure Formed During Static Low-Temperature Annealing of ZnO on the Performance of Inverted Polymer Solar Cells

et al. 2017

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“…Recently, applications of ZnO nanorods and thin films in energy conversion, such as in electronic and optoelectronic devices such as transparent conductors, solar cell windows, gas sensors, surface acoustic wave (SAW) devices, heat mirrors, dye sensitized solar cells and thermoelectronics, have attracted increasing research interest [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Optical and photoluminescence properties of Ga doped ZnO nanostructures by sol-gel method

et al. 2012

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Zinc oxide (ZnO) nanocrystallites with different Ga-doping levels were successfully prepared by spin coating sol-gel technique. The morphological properties of Ga doped ZnO films were studied by atomic force microscopy (AFM). Alignment of ZnO nanorods with respect to the substrate depends on the amount of Ga dopant content. The dopant content varies from 1 % to 4 %, based on Ga-doping levels. The optical properties of the ZnO nanocrystallites following Ga-doping were also investigated by UV-Visible absorption and Photoluminescence spectra. Our results indicate that Gadoping can change the energy-band structure and effectively adjust the intensity of the luminescence properties of ZnO nanocrystallites. Transmittance spectra of the films indicate that the films have high transparency. The refractive index dispersion was analyzed by single oscillator model developed by Wemple and DiDomenico. The oscillator energy, dispersion energy, high frequency dielectric constant values for the films were determined were calculated and it is found that the optical parameters are changed with Ga-doping content.

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“…Thus, the active layer may be penetrated by the ZnO nanorods, and the device's performance is reduced. 32 Therefore, controlling the spin-coating speed of the active layer is an important issue for a device with ZnO NRs.…”

Section: Resultsmentioning

confidence: 99%

ZnO nanorod arrays for various low-bandgap polymers in inverted organic solar cells

Subramani

Kao

et al. 2014

Nanoscale

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Due to the limited diffusion length of carriers in polymer solar cells (PSCs), the path of carriers is a crucial factor that determines the device performance. Zinc oxide nanorods (NRs) as the electron transport channel can reduce electron-hole recombination and transport the electron to the electrode efficiently for poly(3-hexylthiophene) (P3HT), but have been seldom demonstrated for low-bandgap polymers. Here we successfully applied ZnO NRs, which were grown via the hydrothermal method, as a platform to enhance PSC efficiency for various low-bandgap polymers. In order to assure that the nanorod morphology functioned properly for PSCs, the growth time, the concentration, and the resulting morphology were systematically investigated in depths. Such ZnO NRs were applied to different organic systems, resulting in the increase of the PCE for PBDTTT-C/PC71BM from 4.76% to 6.07% and PBDTTT-C-T/PC71BM from 5.40% to 7.34%. Through those experiments, we established a potentially universal and efficient ZnO NRs platform for various low-bandgap polymers to achieve high efficiency of inverted PSCs.

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The influence of wrinkled ZnO on inverted low bandgap thin film solar cells

Cited by 14 publications

References 29 publications

Effects of the Wrinkle Structure and Flat Structure Formed During Static Low-Temperature Annealing of ZnO on the Performance of Inverted Polymer Solar Cells

Effects of the Wrinkle Structure and Flat Structure Formed During Static Low-Temperature Annealing of ZnO on the Performance of Inverted Polymer Solar Cells

Optical and photoluminescence properties of Ga doped ZnO nanostructures by sol-gel method

ZnO nanorod arrays for various low-bandgap polymers in inverted organic solar cells

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