Effect of HCl etching on TiO.sub.2 nanorod-based perovskite solar cells

• Published in: Journal of materials science Vol. 53; no. 21; pp. 15257 - 15270
• Main Authors: Yue, QingWen, Duan, Jinxia, Zhu, Linlu, Zhang, Kai, Zhang, Jun, Wang, Hao
• Format: Journal Article
• Language: English
• Published: Springer 01.11.2018
• Subjects: Annealing; Hydrolysis; Perovskite; Solar cells; Solar energy industry
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-018-2685-6

TiO.sub.2 nanorods (NRs) show unique electron extraction capability for perovskite solar cells (PVSCs). In this work, we gradually optimized TiO.sub.2 compact layers and vertical NRs to improve PVSC performances. TiO.sub.2 compact layers (i.e., barrier layers) from 2-h TiCl.sub.4 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 TiO.sub.2 NRs were also controlled by the hydrothermal time, favoring the infiltration and crystallization of photoactive CH.sub.3NH.sub.3PbI.sub.3. And perovskite photovoltaics achieved the average efficiency of 16.01 ± 0.80% with ~250-nm-long TiO.sub.2 NRs. Finally, the surface feature of TiO.sub.2 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 TiO.sub.2 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 TiO.sub.2 NRs at low-temperature (150 °C) annealing with similar efficiency ~17.41% (16.60 ± 0.81%), which is good for flexible device fabrication.