School of Materials Science and Engineering, Nanchang University, Jiangxi 330031, P. R. China.
Nanoscale. 2019 Feb 14;11(7):3360-3369. doi: 10.1039/c8nr08934e.
Hybrid organic-inorganic perovskite (HOIP) materials have remarkable potential in solar cells owing to their high power conversion efficiency and inexpensive preparation. However, their current-voltage (I-V) curves often exhibit hysteresis characteristics, which not only strongly affect the accuracy of measurements but also seriously impair device performance, and, moreover, their actual origin is still the subject of debate. Here, a single HOIP micro/nanowire-based two-terminal device was constructed. Not only can its hysteresis properties be accurately modulated, but also their origin can clearly be identified as variations in the surface barrier related to trap filling. Under illumination of the entire device with visible (VIS) light, two anticlockwise hysteresis loops appear symmetrically in cyclic I-V curves. Interestingly, the cyclic I-V curves can be switchably changed into asymmetrical "8"-shaped hysteresis loops with bipolar resistive switching (RS) features when only the vicinity of one electrode is illuminated. The traps located in the surface space charge region play a crucial role in the tunable hysteresis behaviour. Owing to the presence of abundant surface states, two back-to-back connected diodes related to the surface barrier can be formed in the two-terminal device. With the synergistic assistance of illumination and bias, moreover, the injection and extraction of holes in the surface space charge region can effectively modulate the surface barrier, which triggers the formation of a bipolar RS device. Accordingly, two switchable back-to-back connected bipolar RS devices were built. Regarding the tunable hysteresis with nonvolatile memory properties controlled by the synergistic action of bias and illumination, our results provide a valuable insight into the identification of its origin and, furthermore, also indicate that the HOIP materials have significant potential in nonvolatile memory applications.
杂化有机-无机钙钛矿（HOIP）材料由于其高的功率转换效率和低廉的制备成本，在太阳能电池中具有显著的潜力。然而，它们的电流-电压（I-V）曲线通常表现出滞后特性，这不仅强烈影响测量的准确性，而且严重损害器件性能，而且，其实际起源仍存在争议。在这里，构建了基于单个 HOIP 微/纳线的两端器件。不仅可以准确地调节其滞后特性，而且可以清楚地确定其起源为与陷阱填充有关的表面势垒的变化。在整个器件用可见光（VIS）光照射下，在循环 I-V 曲线中对称地出现两个逆时针滞后环。有趣的是，当仅一个电极附近被照射时，循环 I-V 曲线可以可切换地变为具有双极电阻开关（RS）特性的不对称“8”字形滞后环。位于表面空间电荷区的陷阱在可调节的滞后行为中起着至关重要的作用。由于存在丰富的表面态，可以在两端器件中形成与表面势垒相关的两个背对背连接的二极管。此外，由于光照和偏压的协同作用，表面空间电荷区中的空穴的注入和提取可以有效地调节表面势垒，从而触发双极 RS 器件的形成。因此，构建了两个可切换的背对背连接的双极 RS 器件。关于由偏压和光照的协同作用控制的具有非易失性存储性能的可调谐滞后，我们的结果为其起源的识别提供了有价值的见解，并且进一步表明 HOIP 材料在非易失性存储应用中具有很大的潜力。
