Vol.:(0123456789) 1 3 J Mater Sci: Mater Electron DOI 10.1007/s10854-017-7792-7 Photovoltaic performance of TiO 2 using natural sensitizer extracted from Phyllanthus Reticulatus Arunachalam Arulraj 1,2  · S. Govindan 1  · S. Vadivel 1  · Balasubramanian Subramanian 2   Received: 4 July 2017 / Accepted: 24 August 2017 © Springer Science+Business Media, LLC 2017 1 Introduction Dye sensitized solar cells (DSSCs) based on the wide band gap semiconducting devices have been extensively studied and are known as next generation solar cell devices owing to their simple and fexible structure along with cost efec- tiveness and high energy conversion efciency [1, 2]. The principle behind the working of a DSSC completely dif- fers from that of a conventional p–n junction solar cell with respect to photon absorption and charge transfer mechanism involved. In DSSC, a porous network of semiconducting material (usually TiO 2 ) serves as a charge transport medium in which a sensitizing dye is chemically absorbed. Upon illumination, electrons are injected from the photo excited dye into the conduction band of TiO 2 , while the holes move towards the counter electrode through the redox electrolyte solution (I − /I 3 − ). Upon applying an external load, the elec- trons reach the counter electrode which in turn reduces tri- iodide ions thereby completing the electrical circuit [3]. In this regard, good energy conversion efciency is achieved under one sun condition (air mass 1.5, 100 mW cm −2 ) [4, 5] in which the performance of the cell mainly depends on the photo-sensitizing ability of the dye. The absorption spec- trum of the sensitizer and the anchorage of the sensitizer to the surface of TiO 2 are important parameters in the deter- mination of the efciency of the cell [6]. Photoconversion efciency exceeding 11% could be obtained with the use of a ruthenium-based sensitizer [7]. In general, transition metal coordination compounds (ruthenium Ru complexes) are used as efective sensitizers, due to their intense charge- transfer absorption in the visible spectrum range however, these complexes contain heavy metal which is undesirable from the environmental aspects. However, the major draw- back of ruthenium polypyridyl complex is associated cost and environmental pollution caused by its use [8]. Hence, Abstract Phyllanthus reticulatus, a natural sensitizer has been extracted from Karunelli fruit for the fabrication of TiO 2 based DSSCs. The extracted dye shows the visible light optical absorption at a wavelength of around 520 nm. The presence of anthocyanin in the dye extract has been identifed by the functional molecular groups such as inter- molecular –OH bond, conjugate C=O stretching vibrations using FTIR. A commercial P25 TiO 2 anatase powder has been employed for the fabrication of photoanode on fuo- rine doped tin oxide (FTO) substrate using Doctor-blade technique. The Platinum (Pt) counter electrode has been prepared using electron beam evaporation technique with a thickness of ~200 nm. To measure the photoconversion ef- ciency of the stacked DSSCs, the electrodes are assembled into a cell module and illuminated by a light source simu- lating AM 1.5 with a light intensity of 100 mW/cm 2 . The freshly prepared sensitizer (P. reticulatus pH ~5.5) exhibits the photo-conversion efciency of 0.19%, while decreasing the pH of the sensitizer (pH ~1.0) enhances the photocon- version efciency to six times (0.69%) higher than that of fresh one. * S. Govindan sengutuvan@yahoo.com Balasubramanian Subramanian subramanianb3@gmail.com 1 University College of Engineering-BIT Campus, Tiruchirappalli 620 024, India 2 CSIR-Central Electrochemical Research Institute, Karaikudi 630 003, India