Tandem photovoltaic cells with a composite intermediate layer

Abstract

We have fabricated and tested tandem photovoltaic cells containing series-connected subcells of the “oxide–organic semiconductor–metal” type. The organic semiconductors were two phthalocyanine dyes (SubPc and PcVO); Al or Ag:Mg were used as capping metallic electrodes. A semitransparent composite metal–oxide layer formed by molybdenum oxide MoO x deposited over an ultrathin Al layer is used to join the subcells. Additionally, a MoO x layer deposited onto glass/ITO substrates serves as an anode buffer in the front subcell, and LiF deposited onto the dye layers serves as a cathode buffer in the front or rear subcells. Upon optimization of the thickness and composition of the intermediate layer, the open circuit voltage U oc amounts to 1.6 V reflecting total summation of the contributions from the each of the subcells at a wide spectral coating from 300–1000 nm. The fill factor in the tandem cell is not worse than in individually made single cells with the same scheme or in disconnected subcells.