LAUSR

TiO2 nanorods (NRs) show unique electron extraction capability for perovskite solar cells (PVSCs). In this work, we gradually optimized TiO2 compact layers and vertical NRs to improve PVSC performances. TiO2 compact layers (i.e., barrier layers) from 2-h TiCl4 hydrolysis could cover the entire surface of FTO substrate, and their photovoltaic cells showed a higher PCE of 13.61% than counterparts for other hydrolysis time. Subsequently, the microstructures of TiO2 NRs were also controlled by the hydrothermal time, favoring the infiltration and crystallization of photoactive CH3NH3PbI3. And perovskite photovoltaics achieved the average efficiency of 16.01 ± 0.80% with ~250-nm-long TiO2 NRs. Finally, the surface feature of TiO2 NRs and its effect to photovoltaic properties were investigated by HCl etching technology. Through careful manipulation of HCl etching process, the charge recombination and current hysteresis were substantially suppressed and the PCE of the TiO2 NRs-based PVSC was raised to 17.57% (16.63 ± 0.94%), which was ~1.05 times to control devices. Meanwhile, we have fabricated the PVSC based on etched TiO2 NRs at low-temperature (150 °C) annealing with similar efficiency ~17.41% (16.60 ± 0.81%), which is good for flexible device fabrication.