Effect of π-electron system in organic dyes for dye-sensitized solar cells

We have evaluated the effect of π-electron system in donor-π-acceptor (d-π-a) based organic dyes and observed the performances in dye sensitized solar cell (dssc). various π-conjugation structures with different molecular arrangements with and without possessed π-conjugation system were successfully evaluated with custom molecular organic dyes d-1,u01,ak-01,ta-st-ca,ba-03 and yf02. the introduction of conjugated p-system in the d-π-a system elevated wide range of absorption spectra from 300 nm to 850 nm wavelength region. the dssc based on dyes d-1,u01,ak-01,ta-st-ca,ba-03 and yf02 showed onset absorption of 525 nm,600 nm,650 nm,550 nm,810 nm and 550 nm correspondingly on the tio2 film. a dip at the ipce spectra in the 350 nm-470 nm wavelength region for dye d-1and u01 were attributed to the competitive absorption of solar spectrum of i3- solution. the ak-01 and ba-03 dyes showed ipce of 70% at the 360 nm-620 nm region and subsequently reaches up to a maximum of 84% at 450 nm. the u01 dye depicts ipce of 70% at 400 nm-560 nm and peaks of 86% at 500 nm within the visible region. the sensitized yf02 dye reaches up to 75% at 350 nm-550 nm. the greater ipce value of ak-01,ta-st-ca,yf02 and ba-03 in the uv zone suggested that these organic dyes successfully surpassed the dip of ipce spectrum in that region. the photovoltaic performances of these sensitizers were verified by incident-photon-to-current conversion efficiency (ipce),open-circuit photovoltage (voc),short-circuit photocurrent density (jsc) and total power conversion efficiency (η). dyes d-1 and u01 were without any π-linker showed η of 3.34% and 6.01% exhibiting jsc of 6.42 ma cm-2 and 10.70 ma cm-2 respectively. dyes with a π-conjugated oligo-phenylenevinylene unit linker showed η of 6.2% (ak-01),5.41% (ta-st-ca) and 5.29 (yf02),dye with a fused dithienothiophene π-conjugated linker showed η of 6.38% (ba-03) respectively. the corresponding jsc of dyes ak-01,ta-st-ca,ba-03 and yf02 were 15.40 ma cm-2,10.10 ma cm-2,16.17 ma cm-2 and 9.19 ma cm-2 followed by voc of 0.640 v,0.718 v,0.595 v and 0.799 v respectively. the comparative analysis of ipce reveals the effect of π-electron of these dyes to increase their corresponding light harvesting ability,reduced dye aggregation and low carrier recombination in dsscs operation. © penerbit umt.