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Technology

This invention is an inverted OPV that traps light to excite an organic electronic material, establishing a flow of electrons from an Ag anode to an ITO cathode. The electrons in this model flow in the opposite direction of a typical OPV. Inverted bilayer OPVs were constructed with layers in the following order from bottom to top: 1) glass, 2) ITO bottom cathode, 3) low work function  PEDOT cathode buffer layer treated with TDAE or Cs2CO3, 4) C60 electron acceptor (40 nm thick), 5) tetraphenyldibenzylperiflanthene (DBP) electron donor (30 nm thick), 6) MoO3 anode buffer layer, and 7) Ag top anode.  Work function measurements showed that TDAE treatment decreased the work function of PEDOT:PSS by 0.6 eV and the work function of CVD PEDOT by 0.8 eV. Cs2CO3 treatment decreased the work functions of both types of PEDOT by 0.3 eV. These low work function PEDOT layers increased the open-circuit voltage (Voc) to 0.9 V, which is comparable to conventional OPVs. In future iterations of this design, current flow through the cell could be could be increased by blending the electron acceptor and electron donor in the center of the structure into a bulk heterojunction or by choosing different materials for the electron acceptor and donor layers (layers 4 and 5).