Yttrium-doped TiO2 compact layers for efficient perovskite solar cells.

To improve the electron transporting and suppress the charge recombination at the interface of TiO 2 /perovskite, the smooth and compact yttrium(Y)-doped TiO 2 compact layers were successfully prepared via a hydrolysis-pyrolysis method. The influences of Y-doped on the microstructure, crystal phase, chemical composition, optical absorption of the TiO 2 compact layers were investigated, and the electron transporting and charge recombination at the TiO 2 /perovskite interface of solar cells were systemically analyzed. The planar perovskite solar cells based on the Y-doped TiO 2 compact layers with a Y/Ti molar ratio of 5% obtained a best photoelectric conversion efficiency (PCE) of 15.52%, comparing with a PCE of 14.05% from the undoped devices. When the 200-nm length 3% Y-doped TiO 2 nanorod arrays were introduced between the 5% Y-doped TiO 2 compact layers and the perovskite thin film, the champion cell achieved a PCE of 18.32% under illumination of simulated AM 1.5 sunlight (100 mA cm−2). To improve the electron transporting and suppress the charge recombination between the interface of TiO 2 and perovskite, the smooth and compact Y-doped TiO 2 compact layers were successfully prepared by hydrolysis-pyrolysis method using an acidic titanium isopropoxide solution in isopropanol and yttrium chloride hexahydrate (YCl 3 ·6H 2 O) was used as the yttrium source. And further by introducing 200 nm length Y-doped TiO 2 nanorod arrays on the Y-doped TiO 2 compact layers, the PCE was improved to 18.32% with J sc of 23.55 mA cm−2, V oc of 1.04 V, and FF of 74.83% and the average PCE of 17.55 ± 0.86% with J sc of 22.83 ± 0.78 mA cm−2, V oc of 1.04 ± 0.02 V, and FF of 73.19 ± 1.79%. Image 1 • Y-doped TiO 2 compact layers were successfully prepared by hydrolysis-pyrolysis method. • Investigating the electron transporting and charge recombination of TiO 2 /perovskite. • By introducing Y-doped TiO 2 nanorod arrays, the PCE was further improved to 18.32%. [ABSTRACT FROM AUTHOR]