Layer-by-layer deposition and photovoltaic property of Ru-based metal–organic frameworks

Abstract

In the present work, thin films of ruthenium based metal–organic frameworks are synthesized using a layer-by-layer (LbL) technique and the film is characterized using XRD, FE-SEM, UV/visible spectroscopy, cyclic voltammetry and photoluminance spectroscopy. Further, the feasibility of the MOF film as a sensitizer in a solar cell is investigated. The HOMO–LUMO level of the frameworks is estimated and is found to be suitable to allow the use of the frameworks as a sensitizer for TiO₂. When TiO₂ mesoporous film is sensitized with the LBL thin film of the frameworks and a Grätzel type liquid junction solar cell is constructed, it demonstrates the cell performance of I_sc = 2.56 mA cm⁻², V_oc = 0.63 V, FF = 0.63, and E_ff = 1.22%. Photoluminescence spectroscopy and electrochemical impedance spectroscopy show that iodine doping into the frameworks is essential to facilitate the photogenerated electron transfer from the frameworks to TiO₂.