摘要
研究了阴离子和阳离子混合型碘系钙钛矿薄膜材料的结构、光学性质及光致发光温度特性.研究发现,阴离子混合型碘系钙钛矿(MAPb(BrxI1-x)3,MA+=CH3NH3^+)随着半径较小的Br离子的比例增加(x=0-0.1),薄膜择优取向生长更明显,其光学带隙从1.43 eV到1.48 eV线性增加.在光抽运下,随着工作温度从10 K升高到125 K,纯碘系钙钛矿(MAPbI3,即x=0)可见区光致发光(PL)的峰位轻微的红移;之后至350 K,发生蓝移.而Br-阴离子混合型钙钛矿薄膜的PL峰位只随温度升高持续蓝移.并且在不同工作温度下,Br-阴离子比例x与PL峰位呈现线性关系.对于纯碘系钙钛矿,其高温段激子结合能是37.5 meV;随着Br-的比例的增加,高温段激子结合能会先增大后减小.当x=0.0333,其薄膜PL半高宽随温度升高展宽幅度最小,具有更好的温度稳定性.通过进一步三重阳离子混合和阴离子调节,获得更加优良的混合型碘系耗钛矿(Cs0.05(FA0.85A0.15)0.95Pb(Br0.15I0.85)3,FA+=HC(NH2)2^+)薄膜,为进一步研制太阳能电池和发光器件奠定了实验基础.
Lead halide perovskite has attracted much attention due to its high absorption coefficient, long carrier diffusion length, low binding energy, and low cost. The stability of intrinsic crystal structure in I-based perovskite can be theoretically estimated by calculating cubic structures factor and octahedral factor.Experimental methods to solve the stability of structure in I-based perovskite could be mainly to either incorporate anions(e.g. Cl^–, Br^–) or mix cations(e.g. Cs^+) into I-based perovskite matrix. Moreover,incorporating Br^– into I-based perovskite leads its band gap to widen, which might be used as a top-cell material to tandem solar cell. However, in order to understand photo-physics process of anion-mixed and/or cation-mixed perovskites, it is essential to further investigate the optical properties such as absorption spectrum, photoluminescence(PL), temperature-dependent PL(TPL) behavior, etc. In this work, anion-mixed and/or cation-mixed perovskite thin films with high quality crystallization and(110) prereferral orientation are synthesized by one-step solution method. All mixed perovskite films are characterized by using X-ray diffraction(Rigaku D MAX-3 C, Cu-Ka, l = 1.54050 A) and X-ray photoelectron spectroscopy(XPS)(Thermo Scientific Escalab 250 Xi). A set of strong peaks of the mixed perovskite films at 14.12° and 28.48°, is assigned to(110)and(220) lattice plane of orthorhombic crystal structure of I-based perovskite, due to preferred orientation. The Pb 4 f and I 3 d doublet peaks, corresponding to Pb^+2 and I^– states, are observed in XPS spectra. It should be noted that in the absence of other valence states of Pb and I component at lower/upper binding energy, the chemical element composition ratio of Pb^+2 and I^– are close to stoichiometric proportion. For optical absorptionspectra, the optical bandgaps of the perovskite films increase with doping concentration of Br^–increasing. For TPL, the perovskite films with x = 0 and x = 0.05 show abnormal red-shifts in a temperatur
作者
蒋泵
陈思良
崔晓磊
胡紫婷
李跃
张笑铮
吴康敬
王文贞
蒋最敏
洪峰
马忠权
赵磊
徐飞
徐闰
詹义强
Jiang Beng;Chen Si-Liang;Cui Xiao-Lei;Hu Zi-Ting;Li Yue;Zhang Xiao-Zheng;Wu Kang-Jing;Wang Wen-Zhen;Jiang Zui-Min;Hong Feng;Ma Zhong-Quan;Zhao Lei;Xu Fei;Xu Run;Zhan Yi-Qiang(SHU-SolarE R&D Laboratory,Shanghai Key Laboratory of High Temperature Superconductors,Department of Physics,Shanghai University,Shanghai 200444,China;State Key Laboratory of Surface Physics and Department of Physics,Key Laboratory of Micro and Nano Photonic Structure(Ministry of Education),Fudan University,Shanghai 200433,China;Department of Electronic Information Materials,Shanghai University,Shanghai 200444,China;School of Information Science and Technology,Fudan University,Shanghai 200433,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第24期262-271,共10页
Acta Physica Sinica
基金
上海市自然科学基金(批准号:17ZR1409600)
国家自然科学基金(批准号:61874027,11527805,61874070)
复旦大学应用表面物理国家重点实验室(批准号:KF2018_08)资助的课题~~
关键词
混合型钙钛矿
变温光致发光
光学性能
激子结合能
hybrid mixed perovskite
temperature-dependent photoluminescence
optical properties
excitonic binding energy
