Structural, optical and excitonic properties of urea grading doped CH3NH3PbI3 thin films and their application in inverted-type perovskite solar cells

Diksha Thakur, Jia Ren Wu, Anjali Chandel, Kai Jen Cheng, Shou En Chiang, Kun Bin Cai, Sheng Hui Chen, Chun Chuen Yang, Yuan Liang Zhong, Chi Tsu Yuan, Ji Lin Shen, Sheng Hsiung Chang

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5 Scopus citations

Abstract

—The structural, optical and excitonic characteristics of urea doped CH3NH3PbI3 (MAPbI3) multi-crystalline thin films were investigated by using the X-ray diffraction patterns, atomic-force microscopic images, absorbance spectra, photoluminescence (PL) spectra and Raman scattering spectra. The surface-sensitive Raman scattering spectra show that the urea small molecules are mainly distributed in the top region of the MAPbI3 thin films and thereby effectively passivating the electron-poor defects (interfacial MA cations) of MAPbI3 thin films. Besides, the thermal annealing temperature and the concentration of urea additive both strongly influence the formation of MAPbI3 thin films, which dominates the photovoltaic performance. The use of 5-wt% urea can increase the open-circuit voltage (VOC) and short-circuit current density (JSC) of the MAPbI3 solar cells from 0.88 V to 19.75 mA/cm2 to 0.94 V and 22.97 mA/cm2, respectively. In addition, the reduced current hysteresis in the J-V curves of the MAPbI3 solar cells can be explained as due to the effective defect passivation in the top region of the MAPbI3 thin film by the oxygen-donors of the urea small molecules.

Original languageEnglish
Article number157660
JournalJournal of Alloys and Compounds
Volume858
DOIs
StatePublished - 25 Mar 2021

Keywords

  • Interfacial MA cations
  • Reduced current hysteresis
  • Surface-sensitive Raman scattering spectra
  • Urea-doped MAPbI thin films

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