Pazos-Outón Luis M, Xiao T Patrick, Yablonovitch Eli
Department of Electrical Engineering and Computer Sciences , University of California, Berkeley , Berkeley , California 94720 , United States.
J Phys Chem Lett. 2018 Apr 5;9(7):1703-1711. doi: 10.1021/acs.jpclett.7b03054. Epub 2018 Mar 21.
Lead halide materials have seen a recent surge of interest from the photovoltaics community following the observation of surprisingly high photovoltaic performance, with optoelectronic properties similar to GaAs. This begs the question: What is the limit for the efficiency of these materials? It has been known that under 1-sun illumination the efficiency limit of crystalline silicon is ∼29%, despite the Shockley-Queisser (SQ) limit for its bandgap being ∼33%: the discrepancy is due to strong Auger recombination. In this article, we show that methyl ammonium lead iodide (MAPbI) likewise has a larger than expected Auger coefficient. Auger nonradiative recombination decreases the theoretical external luminescence efficiency to ∼95% at open-circuit conditions. The Auger penalty is much reduced at the operating point where the carrier density is less, producing an oddly high fill factor of ∼90.4%. This compensates the Auger penalty and leads to a power conversion efficiency of 30.5%, close to ideal for the MAPbI bandgap.
在观察到卤化铅材料具有令人惊讶的高光伏性能且其光电特性与砷化镓相似之后，光伏领域最近对其兴趣激增。这就引出了一个问题：这些材料的效率极限是多少？众所周知，在1个太阳光照下，晶体硅的效率极限约为29%，尽管其带隙的肖克利 - 奎塞尔（SQ）极限约为33%：差异是由于强烈的俄歇复合。在本文中，我们表明甲基碘化铅（MAPbI）同样具有比预期更大的俄歇系数。俄歇非辐射复合在开路条件下将理论外部发光效率降低到约95%。在载流子密度较小的工作点，俄歇损耗大大降低，产生了高达约90.4%的奇怪高填充因子。这补偿了俄歇损耗并导致功率转换效率达到30.5%，接近MAPbI带隙的理想值。
