Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Publication date: 1st March 2014
Inverted hybrid bulk-heterojunction solar cells based on conjugated polymers and fullerene derivatives have attracted much attention due to their numerous advantages. These devices are considered promising candidates as renewable energy resources because of their low weight, low cost, stability and simple fabrication for large area processing [1]. Currently, there is interest in developing new materials to act as an electron collection layer between the active layer and the conductive substrate for these devices [2]. The TiOx thin film has been introduced as an electron collection layer because of its large bandgap (3.7 eV) and well-matched energy levels (valence band up to ~ 8.1 eV and conduction band above ~ 4.4 eV) to block hole collection at the cathode and to facilitate electron injection and transport in the inverted solar cells [3]. However, the slow charge carrier diffusion in a TiOx film increases the probability for charge recombination. A promising alternative to improve the electronic transport is the incorporation of reduced graphene oxide (RGO) into TiOx films. Due to its high surface area and its electron-accepting properties, RGO can be used to enhance charge carrier transport, and consequently to improve the device performance [4].
In this work, RGO was incorporated in electron collection layers based on TiOx in inverted solar cells aiming to decrease charge recombination and increase conversion efficiency. First, we characterized the graphene oxide (GO) obtained by a modified Hummers method [5]. The TiOx/RGO dispersions were prepared from the mixture of GO, Ti(OiPr)4, acetylacetone and ethanol. The dispersions were deposited on FTO by spin casting followed by heat treatment. During this treatment, the GO was thermally reduced forming RGO. The TiOx and TiOx/RGO films were characterized by X-Ray diffraction, Raman spectroscopy, UV-vis spectroscopy, scanning electron microscopy and atomic force microscopy. The solar cells were mounted with the following configuration: FTO | TiOx/RGO | P3HT:PCBM | PEDOT:PSS | Ag. The TiOx/RGO (1.0 wt %) cell provided the following electrical parameters: Jsc of 7.52 mA cm-2, Voc of 0.58 V, FF of 0.40 and a hof 1.74 %. Compared with the TiOx cell, we observed that the incorporation of RGO in the TiOx film showed an increase of 40 % in Jsc and hence an improvement in the conversion efficiency. Due to its conductive properties, the RGO acts as an electron collector in the TiOx film, which facilitates a rapid electron transport resulting in an increase in photocurrent and conversionefficiency.
Figure. (a) UV-vis spectra for the TiOx/RGO | P3HT:PCBM films. (b) J-V characteristics for inverted solar cells using TiOx films, in the absence of or containing different amounts (in weight) of RGO, as electron collection layers, under 1 Sun simulated light AM 1.5G (100 mW cm-2). Active cell area: 0.12 cm2.
[1] Hau, S. K., Yip, H. L., Jen, A. K. Y. A Review on the Development of the Inverted Polymer Solar Cell Architecture. Polymer Reviews. 2010, 50, 474-510. [2] Hadipour, A., Muller, R., Heremans, P. Room temperature solution-processed electron transport layer for organic solar cells. Organic Electronics. 2013, 14, 2379-2386. [3] Sun, H. Y., Weickert, J., Hesse, H. C., Schmidt-Mende, L. UV light protection through TiO2 blocking layers for inverted organic solar cells. Solar Energy Materials and Solar Cells. 2011, 95, 3450-3454. [4] Chen, L., Zhou, Y., Tu, W. G., Li, Z. D., Bao, C. X., Dai, H., Yu, T., Liu, J. G., Zou, Z. G. Enhanced photovoltaic performance of a dye-sensitized solar cell using graphene-TiO2 photoanode prepared by a novel in situ simultaneous reduction-hydrolysis technique. Nanoscale. 2013, 5, 3481-3485. [5] Kovtyukhova, N. I., Ollivier, P. J., Martin, B. R., Mallouk, T. E., Chizhik, S. A., Buzaneva, E. V., Gorchinskiy, A. D. Layer-by-layer assembly of ultrathin composite films from micron-sized graphite oxide sheets and polycations. Chemistry of Materials. 1999, 11, 771-778.
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.