Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO(2) Nanorod Arrays as Electron Transfer Layer

In this paper, N-doped TiO(2) (N-TiO(2)) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO(2) with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO(2). To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO(2) nanorods. Absorption spectra showed higher absorption of visible light for N-TiO(2) than un-doped TiO(2). The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO(2) than to un-doped TiO(2). Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO(2) than that on un-doped TiO(2). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s11671-016-1811-0) contains supplementary material, which is available to authorized users.