A stepwise approach has been applied for the cosensitization of a thiocyanate free Ru sensitizer (SPS-01) with a metal free dye containing thienylfluorene conjugation (JD1) for dye sensitized solar cells (DSSCs). The cosensitized SPS-01 + JD1 based DSSC showed a significant enhancement in both the open circuit voltage (Voc) and the short circuit current (J sc) relative to the individual single dye based DSSCs. The DSSC based on the SPS-01 + JD1 system yielded a Jsc of 15.38 mA cm -2, a Voc of 0.72 V, a fill factor (FF) of 0.76 and a power conversion efficiency (PCE) of 8.30%. This performance was superior to that of the DSSCs sensitized with the individual dyes SPS-01 (PCE = 5.98%) or JD1 (PCE = 4.76%) fabricated under the same conditions. Results show that the JD1 dye effectively overcomes the competitive light absorption by I 3 -/I- and also prevents dye aggregation and reduces the charge recombination. To understand the effects of the charge recombination of the injected electrons with I3 - in the electrolyte, the dark current-voltage characteristics and electrochemical impedance spectra of the DSSCs sensitized with the SPS-01 and SPS-01+JD1 systems were measured. It was observed that the recombination of the electrons in the conduction band with I3 - in the electrolyte in the DSSC sensitized with SPS-01 +JD1 was significantly reduced relative to the DSSC based on SPS-01.
|Number of pages||8|
|Publication status||Published - 1 Jan 2013|