Crystal Engineering for Low Defect Density and High Efficiency Hybrid Chemical Vapor Deposition Grown Perovskite Solar Cells

Annie Ng, Zhiwei Ren, Qian Shen, Sin Hang Cheung, Huseyin Cem Gokkaya, Shu Kong So, Aleksandra B. Djurišić, Yangyang Wan, Xiaojun Wu, Charles Surya

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)

Abstract

Synthesis of high quality perovskite absorber is a key factor in determining the performance of the solar cells. We demonstrate that hybrid chemical vapor deposition (HCVD) growth technique can provide high level of versatility and repeatability to ensure the optimal conditions for the growth of the perovskite films as well as potential for batch processing. It is found that the growth ambient and degree of crystallization of CH3NH3PbI3 (MAPI) have strong impact on the defect density of MAPI. We demonstrate that HCVD process with slow postdeposition cooling rate can significantly reduce the density of shallow and deep traps in the MAPI due to enhanced material crystallization, while a mixed O2/N2 carrier gas is effective in passivating both shallow and deep traps. By careful control of the perovskite growth process, a champion device with power conversion efficiency of 17.6% is achieved. Our work complements the existing theoretical studies on different types of trap states in MAPI and fills the gap on the theoretical analysis of the interaction between deep levels and oxygen. The experimental results are consistent with the theoretical predictions.

Original languageEnglish
Pages (from-to)32805-32814
Number of pages10
JournalACS Applied Materials and Interfaces
Volume8
Issue number48
DOIs
Publication statusPublished - Dec 7 2016
Externally publishedYes

Keywords

  • cooling rates
  • crystallization
  • defects
  • growth ambient
  • hybrid chemical vapor deposition
  • passivation
  • perovskites
  • solar cells

ASJC Scopus subject areas

  • Materials Science(all)

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