退火温度对CH3NH3PbI3薄膜结构和性能的影响

采用真空双源共蒸发技术制备了CH_3NH_3PbI_3薄膜,研究了退火温度对CH_3NH_3PbI_3薄膜结构和性能的影响。利用XRD、原子力显微镜、紫外—可见—近红外分光光度计和霍尔效应仪研究了CH_3NH_3PbI_3薄膜的微观结构和光电性能。研究结果表明:合适的退火温度(95℃)有助于薄膜结晶度的提高,利于晶粒长大,使得晶界减少,界面处缺陷度较低,带电粒子迁移率提高。退火温度超过100℃时,薄膜热稳定性急聚下降,使CH_3NH_3PbI_3分解,部分I-以CH3NH3I的形式挥发,产生大量过剩Pb I2相,导致薄膜载流子浓度降低,导电性能下降。退火后的薄膜在可见光区域内吸收系数提高。退火温度为95℃时,薄膜禁带宽度1.66 e V最小,最接近理论值1.55 e V。

Effects of annealing temperature on microstructures and properties of CH3NH3PbI3thin film

Dual-source physical vapor deposition method was employed to directly deposit the CH3NH3PbI3 thin film.Meanwhile,the influence of annealing temperature on the structure and properties of the film was in-vestigated. XRD,AFM,UV-visible-near infrared spectrophotometer and Hall Effect device were used to study the microstructures and optical and electrical properties of the CH3NH3PbI3film.It was found that the crystallinity of the CH3NH3PbI3film was improved at suitable annealing temperature and,benefited to the grain growth,reduced the grain boundary and increased the mobility of charge carriers.The CH3NH3PbI3was rapidly decomposed at the temperature over 100 ℃,which resulted in the evaporation of I- in the form of CH3NH3I and,left a great number of PbI2and therefore,reduced the carrier concentration and conductivity of the film.After annealing treatment,the absorbtance of the films were improved within the visible light area. At the temperature of 95℃,the band gap of the CH3NH3PbI3film was 1.66 eV,which was the close to the theoretical value of 1.55 eV.