Department of Chemistry and Chemical Engineering, Inha University, Incheon 402-751, Korea.
Nanoscale. 2015 May 21;7(19):8898-906. doi: 10.1039/c5nr01364j.
Single crystalline TiO2 nanoparticles (NPs) with spherical morphology are successfully synthesized by a hydrothermal reaction under basic conditions. TiO2 NPs, selectively controlled to the sizes of 30, 40, 50, and 65 nm, are then applied to a mesoporous photoelectrode of CH3NH3PbI3 perovskite solar cells. In particular, a spherical TiO2 NP of 50 nm size (NP50) offers the highest photovoltaic conversion efficiency (PCE) of 17.19%, with JSC of 21.58 mA cm(-2), VOC of 1049 mV, and FF of 0.759 while the enhancement of PCE mainly arises from the increase of VOC and FF. Furthermore, the fabricated photovoltaic devices exhibit reproducible PCE values and very little hysteresis in their J-V curves. Time-resolved photoluminescence measurement and pulsed light-induced transient measurement of the photocurrent indicate that the device employing NP50 exhibits the longest electron lifetime although the electron injection from perovskite to TiO2 is less efficient than the devices with smaller TiO2 NPs. The extended electron lifetime is attributed to the suppression of electron recombination due to optimized mesopores generated by the spherical NP50.
通过在碱性条件下的水热反应，成功合成了具有球形形态的单晶 TiO2 纳米颗粒（NPs）。然后，将 TiO2 NPs 选择性地控制在 30、40、50 和 65nm 的尺寸，并应用于 CH3NH3PbI3 钙钛矿太阳能电池的介孔光电电极中。特别是，尺寸为 50nm 的球形 TiO2 NP（NP50）提供了最高的光电转换效率（PCE）17.19%，JSC 为 21.58mA cm(-2)，VOC 为 1049mV，FF 为 0.759，而 PCE 的提高主要归因于 VOC 和 FF 的增加。此外，所制备的光伏器件表现出可重复的 PCE 值和在 J-V 曲线中几乎没有滞后现象。时间分辨光致发光测量和脉冲光诱导瞬态光电流测量表明，尽管 NP50 器件中钙钛矿到 TiO2 的电子注入效率不如 TiO2 较小 NPs 器件高，但采用 NP50 的器件表现出最长的电子寿命。扩展的电子寿命归因于优化的介孔对电子复合的抑制，而优化的介孔是由球形 NP50 产生的。
