First-Principles Study of Ion Diffusion in Perovskite Solar Cell Sensitizers
First-Principles Study of Ion Diffusion in Perovskite Solar Cell Sensitizers
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DOI：
10.1021/jacs.5b03615
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发表时间：
2015-08-19
影响因子：
15
通讯作者：
Tateyama, Yoshitaka
中科院分区：
文献类型：
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作者：
Haruyama, Jun;Sodeyama, Keitaro;Tateyama, Yoshitaka
电流-电压曲线中的滞后现象一直是钙钛矿太阳能电池（PSC）转换效率评估和开发的重要问题。本研究采用第一性原理计算方法，研究了四元（MAPbI（3））和三元（NH 2）（2）CHPbI（3）中离子扩散效应.计算出的阴离子和阳离子空位迁移的活化能清楚地表明，MAPbI（3）和FAPbI（3）中的I-阴离子都可以很容易地以低的ca势垒扩散。0.45 eV，与在离子传导材料中观察到的相当。更有趣的是，典型的MA（+）阳离子和较大的FA（+）阳离子都具有相当低的势垒，这表明当施加偏压时，阳离子分子可以在钙钛矿敏化剂中迁移。这些结果可以解释最近提出的离子位移的实验方案。利用稀释扩散理论，我们讨论了较小的空位浓度（较高的结晶度）和用较大的阳离子分子取代MA（+）对于抑制PSC光敏剂的滞后以及防止其老化行为是必不可少的。
Hysteresis in current-voltage curves has been an important issue for conversion efficiency evaluation and development of perovskite solar cells (PSCs). In this study, we explored the ion diffusion effects in tetragonal CH3NH3PbI3 (MAPbI(3)) and trigonal (NH2)(2)CHPbI3 (FAPbI(3)) by first-principles calculations. The calculated activation energies of the anionic and cationic vacancy migrations clearly show that I- anions in both MAPbI(3) and FAPbI(3) can easily diffuse with low barriers of ca. 0.45 eV, comparable to that observed in ion-conducting materials. More interestingly, typical MA(+) cations and larger FA(+) cations both have rather low barriers as well, indicating that the cation molecules can migrate in the perovskite sensitizers when a bias voltage is applied. These results can explain the ion displacement scenario recently proposed by experiments. With the dilute diffusion theory, we discuss that smaller vacancy concentrations (higher crystallinity) and replacement of MA(+) with larger cation molecules will be essential for suppressing hysteresis as well as preventing aging behavior of PSC photosensitizers.