Ni Zhenyi, Xu Shuang, Jiao Haoyang, Gu Hangyu, Fei Chengbin, Huang Jinsong
Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC 27599, USA.
Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA.
Sci Adv. 2022 Sep 9;8(36):eabq8345. doi: 10.1126/sciadv.abq8345. Epub 2022 Sep 7.
Understanding carrier recombination processes in metal halide perovskites is fundamentally important to further improving the efficiency of perovskite solar cells, yet the accurate recombination velocity at grain boundaries (GBs) has not been determined. Here, we report the determination of carrier recombination velocities at GBs () of polycrystalline perovskites by mapping the transient photoluminescence pattern change induced by the nonradiative recombination of carriers at GBs. Charge recombination at GBs is revealed to be even stronger than at surfaces of unpassivated films, with average reaching 2200 to 3300 cm/s. Regular surface treatments do not passivate GBs because of the absence of contact at GBs. We find a surface treatment using tributyl(methyl)phosphonium dimethyl phosphate that can penetrate into GBs by partially dissolving GBs and converting it into one-dimensional perovskites. It reduces the average by four times, with the lowest of 410 cm/s, which is comparable to surface recombination velocities after passivation.
了解金属卤化物钙钛矿中的载流子复合过程对于进一步提高钙钛矿太阳能电池的效率至关重要，但尚未确定晶界（GBs）处的准确复合速度。在此，我们通过绘制由晶界处载流子的非辐射复合引起的瞬态光致发光图案变化，报告了多晶钙钛矿晶界（）处载流子复合速度的测定。结果表明，晶界处的电荷复合甚至比未钝化薄膜表面的电荷复合更强，平均达到2200至3300 cm/s。由于晶界处不存在接触，常规的表面处理无法钝化晶界。我们发现一种使用磷酸二甲基三丁基（甲基）鏻的表面处理方法，它可以通过部分溶解晶界并将其转化为一维钙钛矿而渗透到晶界中。它将平均降低了四倍，最低为410 cm/s，这与钝化后的表面复合速度相当。
