摘要
近年来,有机-无机杂化钙钛矿太阳能电池因其优异的光电转换效率和低廉的制备成本引起了科研工作者的广泛关注,但钙钛矿薄膜中出现的大量缺陷严重制约了电池性能与工作稳定性的进一步提升.本文一方面总结了钙钛矿晶体中各类缺陷的形成过程与物理性质,并分析了各类缺陷对太阳能电池工作的影响;另一方面从界面钝化层出发,综述了以Lewis酸、Lewis碱、有机胺与铵盐、聚合物、金属氧化物、三维钙钛矿、石墨烯和无机盐等材料作为界面钝化层的钝化机制与钝化效果.通过对现有研究成果的分析,总结出有效的界面钝化思路与策略,为钙钛矿太阳能电池界面钝化领域的工作提供一定的参考.
Perovskite,as a class of semiconductor materials with unique optoelectronic properties,such as low exciton binding energy,long carrier diffusion length and tunable bandgap,is widely studied in many research fields.Particularly,organic-inorganic hybrid perovskite solar cells(PSCs)have attracted wide attention due to their low cost and high power conversion efficiencies.Currently,inherent defects in perovskites are restricting their further development.As is known to all,both deep level defects and shallow level defects play key roles in the dynamic process of carriers and the stability of perovskites.Recombination loss,unfavorable band bending,unwanted surface reaction and ionic migration caused by these defects,can lead to serious damages to the device lifetime and performance.In this review article,the formation processes and physical properties of the defects,including point defects,surface defects and defects around perovskite grain boundaries,as well as their effects on the PSC performances,are carefully summarized and analyzed.According to the previous studies,conduction band and valence band of perovskites and defect energy states in perovskites are all related to the anti-bonding coupling of Pb-s and I-p atom orbitals.Certain anti-site and interstitial defects caused by the wrong ionic bonds as well as the surface states can create deep level defects.Moreover,shallow level defects produced by the point defects and grain boundaries will aggravate the unfavorable ion migration and surface reaction,which will dramatically deteriorate the device lifetime and performance of the PSCs.Therefore,defect passivation is a crucial and powerful route to optimizing the power conversion efficiency and long-term stability of the PSCs.Moreover,recent advances in interfacial layer used for the defect passivation,categorized as Lewis acid,Lewis base,alkylammonium,polymer,metal oxide,3 D perovskite,graphene and inorganic salt,are described in detail.We comprehensively present the passivation mechanisms and significant effects of these materials in this paper.Note that the main passivation mechanisms of these materials have been summarized as following:(1)Reducing the density of surface defects via the interaction between functional groups of the passivation molecules and the defects;(2)forming passivation layer on the surface through in situ reaction between the passivation molecules and the perovskite during post-treatment;(3)optimizing the energy level arrangement of the PSCs by molecular dipole to promote the transport and extraction of photo carriers;(4)adding an insulating layer between the active layer and the charge transport layer to improve the stability of the perovskite and the PSCs;(5)controlling the crystallization and wettability of the perovskite film and each function layer through surface interaction to obtain flat and high-quality films.Lastly,some potential design strategies of passivation materials are proposed,such as intentionally integrating multifunction groups,polymerization of small organic molecules and exploring novel inorganic materials.The theoretical understanding of the defects properties and the mechanisms for defect passivation summarized by this review should be very helpful in further developing the PSCs.
作者
牛国盛
庄晶
栾乙刚
曹小飞
王吉政
Guosheng Niu;Jing Zhuang;Yigang Luan;Xiaofei Cao;Jizheng Wang(Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China;School of Chemical Sciences,University of Chinese Academy of Sciences,Beijing 100190,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2021年第17期2179-2201,共23页
Chinese Science Bulletin
基金
国家重点研发计划(2016YFA0200104)资助。
