Research Of The Bifacial Dye-sensitized Solar Cells With Conducting Polymer Counter Electrodes

Energy is one of the most important problems in the world. With increasingconsumption of the conventional fuels, new energy like wind energy, solar energy andnuclear energy and so on, receive great attention. Solar energy because it’s clean,readily available and inexhaustible, is a promising way to solve global energy-relatedproblems. The deployment of conventional silicon solar cells is limited by its highcost. And dye-sensitized solar cells (DSSC) are a promising candidate because of itsenvironment-friend, easy preparation, low cost, high conversion efficiency and gooddurability. However DSSC haven’t exhibited excellent efficiency for over20years,one approach not only to increasing efficiency but also reducing costs are to usebifacial dye-sensitized solar cells (BDSSC), which are based on transparent counterelectrodes. BDSSC are capable of converting the incident light to electricity at thefront and rear side of the cell, resulting in a sufficient utilization of sunlight and theenhancement of power conversion efficiency. This new concept provides a new routefor enhancing the photovoltaic performance of solar cells. The design concept ofBDSSC can be used in other photovoltaic systems with transparent CEs.The specific researches are as follows:1) PANI(ECD) was prepared on the FTO by an electrochemical depositionmethod. The transmittance of PANI(ECD) counter electrode is about3%; Theefficiency of the BDSSC based on PANI(ECD) are almost the same whether thesunlight illuminate from both sides or only the front side. The study approved theuntransparent counter electrodes are not a good candidate for BDSSC.2) In order to improving the transparency of counter electrodes, we fabricatedPANI(CD) counter electrodes via a facile in situ polymerization method. ThePANI(CD) film showed excellent transparency range from350to750nm with itsmaximum transmittance of56.05%at510nm.When illuminating from the rear side, the efficiency of the BDSSC based onPANI(CD) improved713.5%comparing to the PANI(ECD) counter electrode. And the result PANI(CD) film is adhere to the FTO effectively.3) To diminish the interfacial resistance and accelerate the charge transportbetween PANI and FTO glass substrate,4-aminothiophenol (4-ATP) was used asbridging agent with SH end covalently bonded on FTO layer and NH2end guidethe growth of PANI chains to form4-ATP/PANI(CD) film. The resulted4-ATP/PANI(CD) counter electrode shows a lower relative series resistance (RS) andcharge transfer resistance (RCT). As the sunlight irradiate the cell from both sides, theBDSSC based on4-ATP/PANI(CD) counter electrode resulting in a energyconversion efficiency of7.78%, which was higher to that of7.41%when the counterelectrode was switched to Pt. Besides, the transmittance of the4-ATP/PANI(CD)counter electrode has also improved.