title: Covalently Connecting Crystal Grains with Polyvinylammonium Carbochain Backbone To Suppress Grain Boundaries for Long-Term Stable Perovskite Solar Cells.
abstract: Grain boundaries act as rapid pathways for nonradiative carrier recombination, anion migration, and water corrosion, leading to low efficiency and poor stability of organometal halide perovskite solar cells (PSCs). In this work, the strategy suppressing the crystal grain boundaries is applied to improve the photovoltaic performance, especially moisture-resistant stability, with polyvinylammonium carbochain backbone covalently connecting the perovskite crystal grains. This cationic polyelectrolyte additive serves as nucleation sites and template for crystal growth of MAPbI3and afterward the immobilized adjacent crystal grains grow into the continuous compact, pinhole-free perovskite layer. As a result, the unsealed PSC devices, which are fabricated under low-temperature fabrication protocol with a proper content of polymer additive PVAm·HI, currently exhibit the maximum efficiency of 16.3%. Remarkably, these unsealed devices follow an "outside-in" corrosion mechanism and respectively retain 92% and 80% of the initial PCE value after being exposed under ambient environment for 50 days and 100 days, indicating the superiority of carbochain polymer additives in solving the long-term stability problem of PSCs.
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Han
authors.initials: H
authors.lastname: Li
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.|State Centre for International Cooperation on Designer Low-Carbon and Environmental Material (SCICDLCEM), Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Liang
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Yingliang
authors.identifier: http://orcid.org/0000-0001-6515-165X
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.|State Centre for International Cooperation on Designer Low-Carbon and Environmental Material (SCICDLCEM), Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Jincheng
authors.initials: J
authors.lastname: Tong
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zuo
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Shengang
authors.initials: S
authors.lastname: Xu
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.|State Centre for International Cooperation on Designer Low-Carbon and Environmental Material (SCICDLCEM), Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Guosheng
authors.identifier: http://orcid.org/0000-0003-1498-7929
authors.initials: G
authors.lastname: Shao
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University , Zhengzhou 450001, People's Republic of China.
authors.forename: Shaokui
authors.initials: S
authors.lastname: Cao
keywords: covalently connecting; long-term stability; perovskite solar cell; polyvinylammonium; suppressed boundary