Dye Solar Cell Assembly1. Glass handlingTransparent conducting oxide glass (TCO glass) should not be touched with bare fingers. If fingerprints or other contamination are present, clean with ethanol and dry with a hair-dryer .Note:The hazy side, i.e. the one that feels like sticky when passing gently withthe fingernail, is the conducting side for the SnO2 glasses.2. Scotch tape printing of nanocrystalline TiO2 pastesStir well the nanocrystalline TiO2 pastes before use, not shake unless bubbles could be formed.The thickness of the adhesive tape will determine the thickness of the titanium oxide deposited on the glass. We use Scotch Magic tape from 3M, having a thickness of ca. 50 mm. This tape can be easily removed from the glass without leaving traces of adhesive materials.In order to achieve a electrode thickness of ca. 8 mm, two layers of tape are required, although this will depend on the paste concentration used. The transparent pastes (Ti-Nanoxide T or Ti-Nanoxide HT) are made to give a layer of 2-3 mm for a single layer of tape.When using two layers of tape, care must be taken that the dried titanium oxide will not peel off. So a slow dry-out of the solvent and a progressive heating is necessary to ensure optimal adhesion of the titanium oxide layer onto the TCO glass.The deposition process itself consists of spreading out a given volume, of ca. 10ml/cm2 of titanium oxide paste with a rigid squeegee. A good squeegee is, for example, a microscope slide, preferably with polished edges. A glass rod could also do the job.Let dry electrode or gently dry it with a hair-dryer till the solvent is evaporated. With the Ti-Nanoxide D paste, the electrode turns white or slightly translucent upon drying and with a Ti-Nanoxide T or Ti-Nanoxide HT paste it turns transparent. Important: There should be no signs of peeling off. Look also on the back side of the glass electrode and check if there are no air bubbles visible.Once the titanium oxide has been dried, then remove gently the adhesive tapes.Avoid touching the fresh titanium oxide electrode.An alternate to squeegee printing is the far more reproducible screen-printing: the nanocristalline titanium oxide pastes Ti-Nanoxide D/SP , Ti-Nanoxide T/SP and Ti-Nanoxide HT/SP are specially formulated for screen-printing using polyester meshes of 27 wires/inch to 43 wires/inch typically, to give ca 8 to 16 micron thick nanocristalline TiO2 layers once sintered.3. Sintering processThe sintering process allows the titanium oxide nanocrystals to melt partially together , in order to ensure electrical contact and mechanical adhesion on the glass.Good results have been obtained when using a hot air blower to heat up theelectrode to ca. 450C for about half an hour . A heating plate works also fine.While heating up (e.g. rate: 100 C/min) the electrode, first turns brownish (sometimes it releases fumes), and later it turns yellowish-white due to the temperature dependent band-gap narrowing in the pure titanium oxide (anatase).This is the sign that the sintering process is completed and the cooling rate is chosento avoid cracking of the glass. (e.g. cool down from 450C to ca. 60- 80C in 3minutes).If you want to use the electrode immediately for the sensitizer impregnation, keep the electrode at ca. 70C, to avoid water absorption through capillary effects.C for 30To sinter screen-printed electrodes, first they must be dried at 100-120min prior firing at 450-480C for 30 min.4. Sensitizer impregnationThe sensitizer Ruthenium 535 must be dissolved in pure ethanol in a concentration of 20 mg of dye per 100 ml of solution.Put slowly the sintered electrode, heated at ca. 70C into the sens itizer solution, itsface-up. When impregnating large electrodes put them really gently and slowly into the, usually cold, sensitizer solution, in order to avoid cracking of the glass.The impregnation process can be done at room temperature, then it will take ca 5 to10 hours, depending on the actual titaniumoxide layer thickness.So let theelectrode impregnate overnight to be sure.The process can be accelerated when heating the sensitizer solution to ca. 80C (orreflux), so it will take only 1 to 2 hours.A properly impregnated electrode shows no white areas at all ! Especially look on the back side of the glass.Caution: NO WATER SHOULD ENTER SENSITIZER SOLUTIONA sensitizer solution containing water looks orange and not anymore wine-red.Small amount of water , e.g. from ambient humidity, is not critical.Caution:NO WATER SHOULD CONTACT THE IMPREGNATED ELECTRODES,OTHERWISE THE ELECTRODE IS USELESS.Alkaline or neutral water desorbs instantaneously the sensitizer from the titanium oxide layer!Once stained electrodes are sensitive to ambient humidity - they turn orange colored after several weeks of ambient exposure. Such an orange colored electrodecannot work properly.Please note:Do not brea