Department of Materials Science and Engineering and California NanoSystems Institute, University of California , Los Angeles, California 90095, United States.
School of Chemical Engineering, Sungkyunkwan University (SKKU) , Suwon 440-746, Korea.
Nano Lett. 2017 Jul 12;17(7):4270-4276. doi: 10.1021/acs.nanolett.7b01211. Epub 2017 Jun 8.
Anomalous current-voltage (J-V) hysteresis in perovskite (PSK) solar cell is open to dispute, where hysteresis is argued to be due to electrode polarization, dipolar polarization, and/or native defects. However, a correlation between those factors and J-V hysteresis is hard to be directly evaluated because they usually coexist and are significantly varied depending on morphology and crystallinity of the PSK layer, selective contacts, and device architecture. In this study, without changing morphology and crystallinity of PSK layer in a planar heterojunction structure employing FACsPbI, a correlation between J-V hysteresis and trap density is directly evaluated by means of thermally induced PbI regulating trap density. Increase in thermal annealing time at a given temperature of 150 °C induces growth of PbI on the PSK grain surface, which results in significant reduction of nonradiative recombination. Hysteresis index is reduced from 0.384 to 0.146 as the annealing time is increased from 5 to 100 min due to decrease in the amplitude of trap-mediated recombination. Reduction of hysteresis by minimizing trap density via controlling thermal annealing time leads to the stabilized PCE of 18.84% from the normal planar structured FACsPbI PSK solar cell.
钙钛矿（PSK）太阳能电池中的异常电流-电压（J-V）滞后现象存在争议，滞后现象被认为是由于电极极化、偶极子极化和/或本征缺陷引起的。然而，由于这些因素通常共存，并且根据 PSK 层的形态和结晶度、选择性接触和器件结构有很大的变化，因此很难直接评估这些因素与 J-V 滞后之间的相关性。在这项研究中，在不改变平面异质结结构中 PSK 层的形态和结晶度的情况下，通过热诱导的 PbI 调节陷阱密度，直接评估 J-V 滞后与陷阱密度之间的相关性。在 150°C 的给定温度下增加热退火时间会导致 PbI 在 PSK 晶粒表面生长，从而显著降低非辐射复合。由于陷阱介导的复合幅度减小，滞后指数从 0.384 降低到 0.146，随着退火时间从 5 分钟增加到 100 分钟。通过控制热退火时间来最小化陷阱密度从而减少滞后现象，使得正常平面结构的 FACsPbI PSK 太阳能电池的稳定 PCE 达到 18.84%。
