Department of Physics, Imperial College London, London SW7 2AZ, UK.
Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK.
Nat Commun. 2016 Dec 22;7:13831. doi: 10.1038/ncomms13831.
Ion migration has been proposed as a possible cause of photovoltaic current-voltage hysteresis in hybrid perovskite solar cells. A major objection to this hypothesis is that hysteresis can be reduced by changing the interfacial contact materials; however, this is unlikely to significantly influence the behaviour of mobile ionic charge within the perovskite phase. Here, we show that the primary effects of ion migration can be observed regardless of whether the contacts were changed to give devices with or without significant hysteresis. Transient optoelectronic measurements combined with device simulations indicate that electric-field screening, consistent with ion migration, is similar in both high and low hysteresis CHNHPbI cells. Simulation of the photovoltage and photocurrent transients shows that hysteresis requires the combination of both mobile ionic charge and recombination near the perovskite-contact interfaces. Passivating contact recombination results in higher photogenerated charge concentrations at forward bias which screen the ionic charge, reducing hysteresis.
离子迁移被认为是杂化钙钛矿太阳能电池中光伏电流-电压滞后的一个可能原因。该假说的一个主要反对意见是，通过改变界面接触材料可以减少滞后；然而，这不太可能显著影响钙钛矿相内可动离子电荷的行为。在这里，我们表明，无论接触是否改变以使器件具有或不具有显著滞后，都可以观察到离子迁移的主要影响。瞬态光电测量结合器件模拟表明，电场屏蔽与离子迁移一致，在高滞后和低滞后 CHNHPbI 电池中是相似的。对光电压和光电流瞬变的模拟表明，滞后需要可动离子电荷和钙钛矿-接触界面附近的复合的组合。钝化接触复合导致正向偏压下产生更高的光生电荷浓度，从而屏蔽离子电荷，减少滞后。
