Poly(3,4-ethylenedioxythiophene) as a hole conductor in solid state dye sensitized solar cells

All solid state dye sensitized solar cells were fabricated using chemically polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) as a hole transport phase. Treatment of an ionic liquid, 1-ethyl-3-methylimidazolium bis((trifluoromethyl)slufonyl)amide (EMImTf2N) on the electrode after polymerization dramatically improved the I–V characteristics of the cells under the dark. Addition of tert-butylpyridine (tBP) and LiTf2N to EMImTf2N solution provided further improvement of the photovoltaic performance. The conversion efficiency of the EMImTf2N treated cells remained stable at least 45 days without any sealing. This stability was associated with the high stability of PEDOT and EMImTf2N.