Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0656, USA.
Nat Commun. 2014 Dec 15;5:5784. doi: 10.1038/ncomms6784.
The large photocurrent hysteresis observed in many organometal trihalide perovskite solar cells has become a major hindrance impairing the ultimate performance and stability of these devices, while its origin was unknown. Here we demonstrate the trap states on the surface and grain boundaries of the perovskite materials to be the origin of photocurrent hysteresis and that the fullerene layers deposited on perovskites can effectively passivate these charge trap states and eliminate the notorious photocurrent hysteresis. Fullerenes deposited on the top of the perovskites reduce the trap density by two orders of magnitude and double the power conversion efficiency of CH(3)NH(3)PbI(3) solar cells. The elucidation of the origin of photocurrent hysteresis and its elimination by trap passivation in perovskite solar cells provides important directions for future enhancements to device efficiency.
在许多有机金属卤化物钙钛矿太阳能电池中观察到的大光电流滞后现象成为了阻碍这些器件最终性能和稳定性的主要障碍，但其起源尚不清楚。在这里，我们证明了钙钛矿材料表面和晶界上的陷光态是光电流滞后的起源，而沉积在钙钛矿上的富勒烯层可以有效地钝化这些电荷陷光态并消除臭名昭著的光电流滞后。沉积在钙钛矿顶部的富勒烯将陷光密度降低了两个数量级，并将 CH(3)NH(3)PbI(3)太阳能电池的功率转换效率提高了一倍。钙钛矿太阳能电池中光电流滞后的起源及其通过陷光态钝化的消除的阐明为提高器件效率提供了重要的方向。
