Effect of MgO recombination barrier layer on the performance of monolithic-structured solid-state dye sensitized solar cells

In this paper, the optical, structural and electrical properties of pure and magnesium-doped TiO2 nanoparticles (NPs) of different cycles (2, 4, 6 and 8 cycles) were explored systematically. The magnesium-doped TiO2 was synthesised through successive ionic layer adsorption and reaction (SILAR) and deployed into dye sensitised solar cells. The effects of the MgO barrier layer was evaluated . The results show enhanced optical properties with MgO coating with a diminished band gap energy. The X-ray diffraction studies show that the anatase phase was preserved after doping and the dopant does not change the crystalline phase of the TiO2. The SEM results show well-dispersed morphology. For the device with 4 SILAR cycles of MgO, gains in open-circuit voltage, current density and simultaneous increase in efficiency were observed which is attributed to improved charge collection efficiency as electrons diffusing through TiO2 have a better chance of reaching the electrode before recombining. At greater SILAR cycles (6 and 8), losses in photocurrent caused net decrease in efficiencies. The results presented in this report implies that the modification of TiO2 with a metal oxide (MgO) can result to good photon management.