Structure modification of halide perovskite to low-dimensions for efficient Light-Emitting Diodes발광다이오드를 위한 할라이드계 페로브스카이트의 저차원 구조 변화

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Perovskite has a solar cell power conversion efficiency of 22.1% as emerging photovoltaic material. Perovskite has potential as light emitting material because good solar cell materials can be a good light emitting material. Perovskite LEDs has attracted attention as a high color purity display with a narrow FWHM of 20 nm of emission spectrum due to its inherent defect density. However, since the exciton binding energy is low, the excitons easily dissociate to free-carriers and causes low efficiency. So we have formed a low-dimensional perovskite structure which has high exciton binding energy through stoichiometry control. In this study we have spin-coated organic-inorganic hybrid perovskite ($MAPbBr_3$) thin films by controlling molar ratio of MABr/$PbBr_2$ from 1 to 2 in precursor solution. When MABr was excessed than PbBr2, films emit the brightest photoluminescence (PL) light. For MABr/$PbBr_2$ = 2, a new crystal phase found from XRD and FT-IR. It indicates low-dimensional perovskite ($MA_nPbX_{2+n}$) was formed. Moreover we have deposited all-inorganic perovskite ($CsPbBr_3$) thin films by thermal co-evaporation which is vacuum process. And we controlled flux ratio of CsBr/$PbBr_2$ to 0.5, 1 and 2. When flux ratio of CsBr/$PbBr_2$ = 2, films showed the high photoluminescence quantum yield (PLQY) of 70% and it has pure phase of zero-dimensional $Cs_4PbBr_6$ from XRD and Raman spectrum.
Advisors
Shin, Byung Haresearcher신병하researcher
Description
한국과학기술원 :신소재공학과,
Publisher
한국과학기술원
Issue Date
2017
Identifier
325007
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 신소재공학과, 2017.8,[v, 47 p. :]

Keywords

Perovskite▼alight-emitting diodes▼ahigh color purity▼alow-dimensional perovskite▼astructure modification; 페로브스카이트▼a발광 다이오드▼a고 색순도▼a저차원 페로브스카이트▼a구조 변화

URI
http://hdl.handle.net/10203/266475
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=867028&flag=dissertation
Appears in Collection
MS-Theses_Master(석사논문)
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