z Materials Science inc. Nanomaterials & Polymers Free-Standing Graphene/Conducting Polymer Hybrid Cathodes as FTO and Pt-Free Electrode for Quasi-State Dye Sensitized Solar Cells Karthick Ramalingam, [a, b, c] SarojiniJeeva Panchu, [a, b] Ashish Shivaji Salunke, [a] Kamalambika Muthukumar, [a] Ashwin Ramanujam, [a] and Selvaraj Muthiah* [a, b, c] Highly conducting freestanding graphene (FSG) was synthe- sized by the simple vacuum filtration method and utilized as a cathode current collector for (fluorine doped tin oxide) FTO free quasi-dye sensitized solar cell (q-DSSC). Sub- sequently,conducting polymers (CPs) viz., polyaniline (PANI) and poly(3,4-ethylene-di-oxythiophene) (PEDOT) was decorated on FSG surface by electrochemical polymerization which acts as a electrocatalytst for Pt free q-DSSC. Entirely, the FSG/CPs affords as a novel cathode architecture for FTO/Pt free electrode for q- DSSCs. Remarkably, the FSG paper electrode exhibits lower sheet resistance (9-11 W sq -1 ) than the FTO which was directly utilized as current collector. Interestingly, the FSG/CPs based cathode shows an improved electro-catalytic behaviour to- wards tri-iodide reduction and in particularly, the photovoltaic performance of FSG/PEDOT shows power conversion efficiency (PCE) of 5.4 % compared with Pt/FTO of 5.1 %. It can be stated that synergetic effect of FSG/PEDOT proves to be a cost effec- tive and efficientsubstitute for cathodes in q-DSSC. Introduction Quasi-dye sensitized solar cells (q-DSSCs), one of the pioneer- ing inventions of third generation photovoltaics has emerged as a promising photo conversiontechnology for efficient light harvesting. They being low cost alternatives to solid-state sili- con solar cell are a potential solution to energy crisis. [1] They have received a wide spread attention due to their ease in fab- rication and low cost. Typically, conventional DSSC comprises of three major components viz. ruthenium-based sensitizer modi- fied mesoporous TiO 2 photoanode on TCO substrate (ii) (I 3  /I  ) redox electrolyte and (iii) Pt based counter electrode (CE). [2] Among these, CE is an important part to enhance the max- imum power and minimize the recombination kinetics. [3] Tradi- tionally, platinised FTO is utilized as a CE, which facilitates an excellent catalytic behaviour towards tri-iodide reduction. [4] However, high-cost, high temperature processing, flexibility and dissolution of Pt on prolonged exposure with iodide ob- structs DSSC commercialization. [5, 6] With regards to this issue, it is necessary to develop a cheap CE that shows excellent elec- trocatalytic activity towards triiodide and rapid charge transfer ability along with stability for a long time. There have been re- cent advancements considering the use of conducting polymer (CP) as a potential alternative to the Pt based counter elec- trode. CPs such as poly(3,4-ethylene-di-oxythiophene) (PE- DOT),polypyrrole (PPy) and polyaniline (PANI) have been esti- mated to enhance the electro-catalytic activity. [7, 8] In addition to this fact, the PEDOT and PANI have excellent redox behaviour with faster charge transfer ability because of its organic semi- conductor nature. [9, 10] Apart from this, carbonaceous materials such as carbon black, carbon nanotubes (CNT), graphite and graphene also have high charge transfer ability and possessing multi-edges present surface defects acting as active centre for electrochemical catalytic reaction. [11] Among all these graphene, 2D hexagonal carbon atom lattice exhibits an excellent elec- trical property, high mechanical strength, large surface area and good thermal stability. [12] The symbiosis of graphene with CPs features excellent redox behaviour coupled with electrical con- ductivity. Hence, graphene can be used as a substituent to FTO as a current collector. To the best of our knowledge, there are only few reports for TCO and Pt free counter electrodes for DSSC application that includes PEDOT, polypyrrole/Au, free- standing polypyrrole, TiC, WO3 and VN. [13–16] In general, CP based CEs are prepared by electrochemical polymerization, interfacial polymerization and chemical poly- merization. Specifically in chemical polymerization, the CP based CEs have been prepared as follows; (i) slurry formation with addition of binders, (ii) deposition on FTO substrate by spin coating or doctor-blade method and (iii) annealing proc- ess. These processes hinderthe electrical resistivity upon addi- tion of binders and the poor adhesion of CP on FTO substrate restricts the catalytic performance. Whereas the electro- [a] K. Ramalingam, S. Panchu, A. S. Salunke, K. Muthukumar, A. Ramanujam, Dr. S. Muthiah CSIR-Central Electrochemical Research Institute, Karaikudi Tamil Nadu, India. Pin – 630003. E-mail: selvaraj58@gmail.com karthick.enviro@gmail.com [b] K. Ramalingam, S. Panchu, Dr. S. Muthiah CSIR-Network of Institutes for Solar Energy CSIR-Central Electrochemical Research Institute, Karaikudi Tamil Nadu, India. Pin – 630003. [c] K. Ramalingam, Dr. S. Muthiah CSIR-Academy of Scientific & Innovative Research CSIR Campus Taramani, Chennai – 600113Tamil Nadu, India. Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/slct.201600874 Full Papers DOI: 10.1002/slct.201600874 4814 ChemistrySelect 2016, 1, 4814 – 4822  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim