Solution-processable MoOx nanocrystals enable highly efficient reflective and semitransparent polymer solar cells

L.K. Jagadamma, H.L. Hu,T. Kim, G.O.N. Ndjawa, A.E. Mansour, A. El Labban, J.C.D. Faria, R. Munir, D.H. Anjum, M.A. McLachlan, A. Amassian
Nano Energy, 28, 277-287, (2016)

Solution-processable MoOx nanocrystals enable highly efficient reflective and semitransparent polymer solar cells

Keywords

Organic solar cells, Polymer solar cells, Molybdenum oxide, Hole transporting layer, Hole injection layer, Semitransparent solar cells, Silver nanowire electrode, Transparent electrode

Abstract

Solution-manufacturing of organic solar cells with best-in-class power conversion efficiency (PCE) will require all layers to be solution-coated without compromising solar cell performance. To date, the hole transporting layer (HTL) deposited on top of the organic bulk heterojunction layer in the inverted architecture is most commonly an ultrathin (<10 nm) metal oxide layer prepared by vacuum-deposition. Here, we show that an alcohol-based nanocrystalline MoOx suspension with carefully controlled nanocrystal (NC) size can yield state of the art reflective and semitransparent solar cells. Using NCs smaller than the target HTL thickness (∼10 nm) can yield compact, pinhole-free films which result in highly efficient polymer:fullerene bulk heterojunction (BHJ) solar cells with PCE=9.5%. The solution processed HTL is shown to achieve performance parity with vacuum-evaporated HTLs for several polymer:fullerene combinations and is even shown to work as hole injection layer in polymer light emitting diodes (PLED). We also demonstrate that larger MoOx NCs (30–50 nm) successfully composite MoOx with Ag nanowires (NW) to form a highly conducting, transparent top anode with exceptional contact properties. This yields state-of-the-art semitransparent polymer: fullerene solar cells with PCE of 6.5% and overall transmission >30%. The remarkable performance of reflective and semitransparent OPVs is due to the uncommonly high fill factors achieved using a carefully designed strategy for implementation of MoOx nanocrystals as HTL materials.

Code

DOI: 10.1016/j.nanoen.2016.08.019

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