Shen Heping, Jacobs Daniel A, Wu Yiliang, Duong The, Peng Jun, Wen Xiaoming, Fu Xiao, Karuturi Siva K, White Thomas P, Weber Klaus, Catchpole Kylie R
Research School of Engineering, The Australian National University , Canberra, Australian Capital Territory 2601, Australia.
Australian Centre for Advanced Photovoltaics, University of New South Wales , Sydney 2052, Australia.
J Phys Chem Lett. 2017 Jun 15;8(12):2672-2680. doi: 10.1021/acs.jpclett.7b00571. Epub 2017 Jun 5.
J-V hysteresis in perovskite solar cells is known to be strongly dependent on many factors ranging from the cell structure to the preparation methods. Here we uncover one likely reason for such sensitivity by linking the stoichiometry in pure CHNHPbI (MAPbI) perovskite cells with the character of their hysteresis behavior through the influence of internal band offsets. We present evidence indicating that in some cells the ion accumulation occurring at large forward biases causes a temporary and localized increase in recombination at the MAPbI/TiO interface, leading to inverted hysteresis at fast scan rates. Numerical semiconductor models including ion accumulation are used to propose and analyze two possible origins for these localized recombination losses: one based on band bending and the other on an accumulation of ionic charge in the perovskite bulk.
众所周知，钙钛矿太阳能电池中的J-V滞后现象强烈依赖于许多因素，从电池结构到制备方法。在这里，我们通过内部带隙偏移的影响，将纯CHNHPbI（MAPbI）钙钛矿电池中的化学计量与滞后行为的特征联系起来，揭示了这种敏感性的一个可能原因。我们提供的证据表明，在一些电池中，大正向偏压下发生的离子积累会导致MAPbI/TiO界面处的复合暂时局部增加，从而在快速扫描速率下导致反向滞后。包括离子积累的数值半导体模型被用来提出和分析这些局部复合损失的两个可能来源：一个基于能带弯曲，另一个基于钙钛矿本体中离子电荷的积累。
