Bertoluzzi Luca, Belisle Rebecca A, Bush Kevin A, Cheacharoen Rongrong, McGehee Michael D, O'Regan Brian C
Department of Materials Science and Engineering , Stanford University , 476 Lomita Mall , Stanford , California 94305 , United States.
Sunlight Scientific , Berkeley , California 94707 , United States.
J Am Chem Soc. 2018 Oct 10;140(40):12775-12784. doi: 10.1021/jacs.8b04405. Epub 2018 Sep 24.
We apply a series of transient measurements to operational perovskite solar cells of the architecture ITO/PTAA/FACsPb(IBr)/C60/BCP/Ag, and similar cells with FAMA. The cells show no detectable JV hysteresis. Using photocurrent transients at applied bias we find a ∼1 ms time scale for the electric field screening by mobile ions in these cells. We confirm our interpretation of the transient measurements using a drift-diffusion model. Using Coulometry during field screening relaxation at short circuit, we determine the mobile ion concentration to be ∼1 × 10/cm. Using a model with one mobile ion species, the concentration and the screening time require an ion mobility of ∼3 × 10 cm/(V s). As far as we know, this article gives the first direct measurement of the ion mobility and concentration in a fully functional perovskite solar cell. The measured ion mobility is 2 orders of magnitude higher than the highest estimates previously determined using perovskite solar cells and perovskite thin films, and 3 orders of magnitude higher than is frequently used in modeling hysteresis effects. We provide evidence that the fast field screening is due to mobile ions, as opposed to dark injection and trapping of electronic carriers.
我们对结构为ITO/PTAA/FACsPb(IBr)/C60/BCP/Ag的工作中的钙钛矿太阳能电池以及具有FAMA的类似电池进行了一系列瞬态测量。这些电池未显示出可检测到的电流电压滞后现象。利用施加偏压下的光电流瞬态，我们发现这些电池中移动离子进行电场屏蔽的时间尺度约为1毫秒。我们使用漂移扩散模型证实了对瞬态测量结果的解释。在短路时的场屏蔽弛豫过程中使用库仑法，我们确定移动离子浓度约为1×10/cm。使用具有一种移动离子种类的模型，浓度和屏蔽时间要求离子迁移率约为3×10 cm/(V s)。据我们所知，本文首次直接测量了全功能钙钛矿太阳能电池中的离子迁移率和浓度。测得的离子迁移率比先前使用钙钛矿太阳能电池和钙钛矿薄膜确定的最高估计值高2个数量级，比常用于模拟滞后效应的值高3个数量级。我们提供证据表明，快速场屏蔽是由移动离子引起的，而不是电子载流子的暗注入和俘获。
