Integration of solution processed novel graphenaceous materials as functional layers in dye sensitized and polymer solar cells

Abstract

Harnessing renewable solar energy through different technologies is greatly dependent on the advancement of solar grade materials’ science and engineering. Worldwide, scientists and engineers are focusing on developing novel solar cell designs which can be easily manufactured at low cost. In this context, 3rd generation (3G) solar energy technologies namely Gratzel cells or Dye Sensitized Solar Cells (DSSCs) and Bulk heterojunction organic photovoltaics (BHJ OPV) are expected to challenge the performance of Si based solar cells and compete for a significant market share in the field of next generation solar cells. These technologies gained prominence due to their low cost, light weight construction and printable nature over large area flexible substrates. This thesis work demonstrates an integration of inexpensive novel Graphenaceous Materials solution, for the above mentioned solar technologies energy harvesting, explore selection of suitable material for their energy efficient utilization and fabrication method. Initially, Graphene oxide (GO) was synthesized using a modified Hummers method and was reduced by using focused sunlight to obtain solar reduced graphene oxide (SRGO). GO and SRGO are then used as Pt free counter electrode materials in dye sensitized solar cells (DSSCs). GO and SRGO counter electrodes were prepared by a simple spray coating method to produce homogeneous electrode layers. The DSSCs with GO and SRGO counter electrodes exhibited an overall power conversion efficiencies of ~3.4 and ~4%, respectively. Cyclic voltammetry and electrochemical impedance spectroscopy reveal that the DSSC with SRGO counter electrode exhibits higher electro-catalytic activity and lower charge transfer resistance at the electrode/electrolyte interface (in comparison to the DSSC with GO) resulting in higher conversion efficiency. Moreover, the microstructural features of SRGO are found to be suitable for its improved interaction with the liquid electrolyte and the enhanced electro-catalytic activity at its surface.