Surface passivation engineering strategy to fully-inorganic cubic CsPbI perovskites for high-performance solar cells
Authors: Yanan Zhang
Lin Fu
Longwei Yin
Tong Yu
Luyuan Zhang
Bo Li
Shujie Zhou
Journal: Nature Communications (2018)
Discipline: Multidisciplinary
Keywords: perovskite solar cells; inorganic perovskite; cesium lead halides; stability; photovoltaic performance
Affiliations: Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, School of Materials Science and Engineering, Shandong University, Jinan, 250061, P. R. China., Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, School of Materials Science and Engineering, Shandong University, Jinan, 250061, P. R. China. .

Abstract:  Owing to inevitable thermal/moisture instability for organic-inorganic hybrid perovskites, pure inorganic perovskite cesium lead halides with both inherent stability and prominent photovoltaic performance have become research hotspots as a promising candidate for commercial perovskite solar cells. However, it is still a serious challenge to synthesize desired cubic cesium lead iodides (CsPbI3) with superior photovoltaic performance for its thermodynamically metastable characteristics. Herein, polymer poly-vinylpyrrolidone (PVP)-induced surface passivation engineering is reported to synthesize extra-long-term stable cubic CsPbI3. It is revealed that acylamino groups of PVP induce electron cloud density enhancement on the surface of CsPbI3, thus lowering surface energy, conducive to stabilize cubic CsPbI3 even in micrometer scale. The cubic-CsPbI3 PSCs exhibit extra-long carrier diffusion length (over 1.5 μm), highest power conversion efficiency of 10.74% and excellent thermal/moisture stability. This result provides important progress towards understanding of phase stability in realization of large-scale preparations of efficient and stable inorganic PSCs. 

Retracted: No

PubPeer comments:
 Fig. 1 Structure and morphology of CsPbI3 films and CsPbI3 perovskite solar cell. a X-ray diffraction (XRD) spectra of CsPbI3 with orthorhombic phase (u03b4, black line), cubic phase (u03b1, red line) and stable cubic phase aging 80 days (blue line). Two identical XRD patterns ![file] , 
 #1 Dear Prof. Thallarcha Lechrioleuca Thanks for your comment and concern about our work. I am the first author of this article. After we saw your comment about Figure 1, we carefully rechecked the data and summarized the possible reasons causing the similar shape for these two patterns as following: 1.tThese two XRD patterns are from the same sample, one is fresh and the other is stored for 80 days. The similarity but different for the XRD patterns between after 80 days and the fresh sample can clearly indicate the phase stability of the perovskite. 2.tPresenting multiple pieces of data in one image may cause the decrease of the resolution, resulting in the easily overlooked deviations which cannot be observed at low resolution. In fact, it is shown that there is an obvious difference between these two patterns when we reproduced the processing details of these two original data according to our previous operations. 1.tThe original data of Sample-fresh and Sample-80d are processed in the JADE 5.0 (software for processing XRD data). Figure a shows the screen capture images of original data of Sample-fresh and Sample-80d. 2.tFor removing the noise signals reasonably, we preformed smoothing procedure in JADE 5.0 for 4 times as shown in Figure b-e. The smoothed XRD patterns of Sample-fresh and Sample-80d are shown in Figure e. 3.tThen, the smoothed data were copied and then pasted into the Origin 8.0 for direct drawing (Figure 1f). For a clear comparison, we put the two patterns together as shown in Figure g and h. It is obvious that these two XRD patterns are different. 4.tAt last, we put all the patterns in one image as shown in Figure i and j. The followings are the screen capture images of original XRD and smoothed XRD patterns. ![file] ![file] Here are the details we provided, and we hope this solves your confusion. In the future, we will pay more attention to the impact of data smoothing to eliminate the concerns to our works. Regards Bo Li , 
 Thank you for reply. Smoothing two different XRD patterns will never produce that level of similarity for random noise in my opinion. ,