Bifacial 8.3%/5.4% front/rear Efficiency Zno:Al/N-Si Heterojunction Solar Cell Produced by Spray Pyrolysis

Untila, G. G., Kost, T. N., & Chebotareva, A. B. (2016). Bifacial 8.3%/5.4% front/rear efficiency ZnO: Al/n-Si heterojunction solar cell produced by spray pyrolysis. Solar Energy, 127, 184-197.

Abstract-Using an as-deposited Al-doped ZnO (AZO) film synthesized by ultrasonic spray pyrolysis directly onto crystalline silicon (c-Si), we demonstrate a bifacial AZO/n-Si heterojunction solar cell (HJSC) with high efficiency of 8.3%/5.4% under front/rear illumination. To optimize fabrication process, the influence of substrate temperature TD(in the range 310–460 °C), annealing, and film thickness d on the film and AZO/c-Si junction properties were studied systematically. SEM, ellipsometry, EDX spectroscopy, transmission, reflection, and external quantum efficiency spectra, resistivity ρ, Hall, Suns–Voc, and light I–V measurements were used for the analysis. Annealed junctions, AZO/n-Si and AZO/p-Si, as well as AZO/p-Si junction with as-deposited films showed small open-circuit voltage Voc (<300 mV). The highest Voc (∼480 mV) showed AZO/n-Si junction with as-deposited film grown at 410 °C. We employed as-deposited AZO films grown at 410 °C in AZO/(nn+)Cz-Si/In2O3:F bifacial heterojunction solar cells, which differed only in the AZO film thickness. Increasing d from 260 to 910 nm resulted in the following: (1) the photocurrent did not changed; (2) ρ and Rsh of the film, Voc and the series resistance of the HJSCs decreased; (3) the fill factor FF and efficiency η increased (for front illumination, FF: from 29.1 to 57.3%, η: from 3.3 to 8.3%, respectively). At rear illumination, the best cell showed the efficiency of 5.4%. At 1-sun front illumination and 20–50–100% 1-sun rear illumination, such a cell will generate energy approaching that produced by a monofacial solar cell of 9.1–10.3–12.1% efficiency.

Keywords: Heterojunction solar cells; Silicon; Al-doped zinc oxide; Ultrasonic spray pyrolysis;Electrical properties; Optical properties


Fabricating TiO2 Film With a Facile Spray-Coating Technique for Dye-Sensitized Solar Cells

Song, Q., Zhu, Y., Zheng, H., Zhang, F., & Wu, M. (2016). Fabricating TiO 2 film with a facile spray-coating technique for dye-sensitized solar cells.Materials & Design, 98, 108-112.

Abstract-Mesoporous TiO2 film is fabricated with simple spray-coating technique for dye-sensitized solar cells (DSCs) and the properties of this kind of TiO2 film are evaluated, compared to those prepared with conventional screen-printing and doctor-blading methods. Scanning electron microscope, N2 adsorption-desorption isotherms, and electrochemical impedance spectroscopy results demonstrate that the TiO2 film prepared with spray-coating method shows high porosity, large BET surface area, and fast charge transfer rate, indicating this method is suitable for preparing mesoporous TiO2 films. The power conversion efficiency of the rigid DSCs using spray-coating method is up to 7.1%, higher than those using screen-printing and doctor-blading techniques (6.6% and 6.2%). In addition, the spray-coating method is special for fabricating large scaled (2.7 cm2) flexible DSCs in low temperature, and an efficiency of 2.4% is achieved.

Keywords: Solar cell; Spray; TiO2; Thin film; Dye


Fine-Tuning the Sn Content in CZTSSe Thin Films to Achieve 10.8% Solar Cell Effi ciency from Spray-Deposited Water–Ethanol-Based Colloidal Inks

Larramona, G., Levcenko, S., Bourdais, S., Jacob, A., Choné, C., Delatouche, B., ... & Dennler, G. (2015). Fine‐Tuning the Sn Content in CZTSSe Thin Films to Achieve 10.8% Solar Cell Efficiency from Spray‐Deposited Water–Ethanol‐Based Colloidal Inks. Advanced Energy Materials, 5(24).

Abstract-Thin film solar cells with Al/ITO/ZnO/CdS/CZTSSe/Mo-glass structure are fabricated employing a fast and low-cost preparation procedure using an aqueous ink deposited by nonpyrolytic spray, followed by high temperature crystallization and selenization steps. Capacitance–voltage measurements on previously reported devices with >8% efficiency under 1 sun irradiation show a charge carrier density of the order of 1017 cm−3. Moreover, admittance spectroscopy indicates the presence of mid-bandgap defects that are tentatively attributed to a Sn deficit in the film. In order to reduce the number of these deep defects within the active layer of our solar cells, the Sn content is tuned in the precursor ink. Their morphology, elemental composition, crystal phases, capacitance–voltage profiling, admittance, photoluminescence, and photovoltaic performances are characterized. The results indicate that tuning the Sn content offers a strong leverage upon some key properties of the active layer, in particular the grain size, and the charge carrier and defect density. By employing this leverage to optimize the performance of our CZTSSe layers, the cell performances are increased to 10.0% without antireflection coating (ARC) and to 10.8% (on 0.25 cm2) with an ARC.


High Efficiency Arrays of Polymer Solar Cells Fabricated by Spray-Coating in Air

Zhang, Y., Griffin, J., Scarratt, N. W., Wang, T., & Lidzey, D. G. (2015). High efficiency arrays of polymer solar cells fabricated by spray‐coating in air.Progress in Photovoltaics: Research and Applications.

Abstract- We present bulk heterojunction organic solar cells fabricated by spray-casting both the PEDOT:PSS hole-transport layer (HTL) and active PBDTTT-EFT:PC71BM layers in air. Devices were fabricated in a (6 × 6) array across a large-area substrate (25 cm2) with each pixel having an active area of 6.45 mm2. We show that the film uniformity and operational homogeneity of the devices are excellent. The champion device with spray cast active layer on spin cast PEDOT:PSS had an power conversion efficiency (PCE) of 8.75%, and the best device with spray cast active layer and PEDOT:PSS had a PCE of 8.06%. The impacts of air and light exposure of the active layer on device performance are investigated and found to be detrimental.


Ultrafast Fabrication of Flexible Dye-Sensitized Solar Cells by Ultrasonic Spray-Coating Technology

Han, H. G., Weerasinghe, H. C., Kim, K. M., Kim, J. S., Cheng, Y. B., Jones, D. J., ... & Kwon, T. H. (2015). Ultrafast Fabrication of Flexible Dye-Sensitized Solar Cells by Ultrasonic Spray-Coating Technology. Scientific reports, 5.

Abstract-This study investigates novel deposition techniques for the preparation of TiO2 electrodes for use in flexible dye-sensitized solar cells. These proposed new methods, namely pre-dye-coating and codeposition ultrasonic spraying, eliminate the conventional need for time-consuming processes such as dye soaking and high-temperature sintering. Power conversion efficiencies of over 4.0% were achieved with electrodes prepared on flexible polymer substrates using this new deposition technology and N719 dye as a sensitizer.