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    Construction of perovskite solar cells using inorganic hole-extracting components

    , Article ACS Omega ; Volume 3, Issue 1 , 4 January , 2018 , Pages 46-54 ; 24701343 (ISSN) Nouri, E ; Mohammadi, M. R ; Lianos, P ; Sharif University of Technology
    American Chemical Society  2018
    A NiOx−graphene oxide (NiOx−GO) hybrid has been prepared by a simple solution-processed method and was used as hole-extraction material in perovskite solar cells with either gold or carbon as back contact electrode. The impact of GO content on the optoelectronic behavior of NiOx and the photovoltaic performance of the fabricated devices has been studied. Thus, GO incorporation showed a significant improvement in the performance of NiOx-based devices. The best attained efficiency was 13.3%, and it was 45% higher than that with pure NiOx. This is attributed to a significant improvement in the hole extraction, recombination resistance, and energy-level matching in comparison to pure NiOx. In... 

    Reducing surface recombination by a poly(4-vinylpyridine) interlayer in perovskite solar cells with high open-circuit voltage and efficiency

    , Article ACS Omega ; Volume 3, Issue 5 , 2018 , Pages 5038-5043 ; 24701343 (ISSN) Yavari, M ; Mazloum Ardakani, M ; Gholipour, S ; Tavakoli, M. M ; Taghavinia, N ; Hagfeldt, A ; Tress, W ; Sharif University of Technology
    American Chemical Society  2018
    Identifying and reducing the dominant recombination processes in perovskite solar cells is one of the major challenges for further device optimization. Here, we show that introducing a thin interlayer of poly(4-vinylpyridine) (PVP) between the perovskite film and the hole transport layer reduces nonradiative recombination. Employing such a PVP interlayer, we reach an open-circuit voltage of 1.20 V for the best devices and a stabilized efficiency of 20.7%. The beneficial effect of the PVP interlayer is proven by statistical analysis of various samples, many of those showing an open-circuit voltage larger than 1.17 V, and a 30 mV increase in average compared to unmodified samples. The reduced... 

    Coupled ionic-electronic equivalent circuit to describe asymmetric rise and decay of photovoltage profile in perovskite solar cells

    , Article Scientific Reports ; Volume 9, Issue 1 , 2019 ; 20452322 (ISSN) Ebadi, F ; Aryanpour, M ; Mohammadpour, R ; Taghavinia, N ; Sharif University of Technology
    Nature Publishing Group  2019
    In this research, we employed transient photo-voltage rise and decay measurements to investigate the origin of slow unsymmetrical rise and decay profiles in single and triple cation perovskite solar cells. Drastic changes in photo-voltage decay profile were observed upon insertion of Br−, Cs+ and FA+ ions into perovskite structures. In order to explain our observations, the activation energy for ionic defects was measured and an equivalent circuit model was proposed containing both electrical and ionic components. The electrical branch consists of a diode, the bulk capacitance and resistances for charge transport and recombination. In parallel we introduced an ionic branch describing the... 

    Vapor assisted deposition of alkaline doped perovskites: Pure phase formation of CsxMA1−xPbI3

    , Article Electrochimica Acta ; Volume 259 , 2018 , Pages 485-491 ; 00134686 (ISSN) Sedighi, R ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
    Elsevier Ltd  2018
    Alkaline doping (Cs, Rb) in CH3NH3PbI3 (MAPbI3) is known to enhance the stability of perovskite solar cells. The films are usually deposited using anti-solvent method, which is tricky and not applicable for large scale deposition. Besides, in case of CsxMA1−xPbI3 the amount of Cs must be carefully controlled to prevent CsI phase formation. Herein, we report an atmospheric pressure vapor assisted solution process (AP-VASP) for the growth of Cs doped MAPbI3 perovskite films that features highly uniform morphology, pin-hole free films, large grain size, as well as being scalable. The CsxMA1−xPbI3 films are formed by the reaction of Cs doped PbI2 films with MAI vapor in a simple oven. We...