TCO-free dye solar cells based on Ti back contact electrode by facile printing method

The back contact dye solar cells (BCDSCs), in which the TCO(Transparent Conductive oxide) is omitted, have a potential for use of intact low-cost general substrates such as glass, metal foil and papers. Herein, we introduce a facile manufacturing method of a Ti back contact electrode (Ti BCE) for the BCDSCs. We found that the polylinkers such as poly(butyl titanate) have a strong binding property to make Ti particles connect one with another. A porous Ti film, which consists of Ti particles of ≤ 10㎛ size connected by a small amount of polylinkers, has an excellent low sheet resistance of 10 Ω sq-1 for an efficient electron collection for DSCs. This Ti BCE can be prepared by using a facile printing method under normal ambient conditions. Conjugating the new back contact electrode technology with the traditional monolithic structure using the carbon counter electrode, we fabricated TCO-less DSCs. These four-layer structurered DSCs consist of a dye-adsorbed nanocrystalline TiO2 film on a glass substrate, a porous Ti back contact layer, a ZrO2 spacer layer and a carbon counter electrode in a layered structure. Under AM 1.5 G and 100 mWcm−2 simulated sunlight illumination, the four-layer structurered DSCs with N719 dyes and I-/I3-redox electrolytes achieved PCEs up to 5.21 %.