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Metal–Organic Framework for Efficient Electron Injection
Author(s) -
He Gufeng,
Zhou Xiaowen,
Liu Jun,
Gong Yongyang,
Wu Xinkai,
Yuan Wangzhang
Publication year - 2021
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202002053
Subject(s) - materials science , work function , x ray photoelectron spectroscopy , indium tin oxide , formic acid , ultraviolet photoelectron spectroscopy , oled , metal , aqueous solution , analytical chemistry (journal) , chemical engineering , layer (electronics) , nanotechnology , chemistry , organic chemistry , engineering , metallurgy
Abstract A 3D metal–organic framework (MOF) [(H 3 O)Zn(HCOO) 3 ] ∞ is developed as a highly efficient and air‐stable solution‐processed electron injection layer (s‐EIL). The [(H 3 O)Zn(HCOO) 3 ] ∞ film can be easily obtained by annealing a spin‐coated [Zn(HCOO) 2 (H 2 O) 2 ] ∞ film at 120 °C in air, which is facilely prepared by the reaction of ZnO powder with formic acid and the aqueous solution of ammonium. The un‐encapsulated electron‐only device with [(H 3 O)Zn(HCOO) 3 ] ∞ as the s‐EIL exhibits significantly enhanced electrical property and air stability, compared to that with vacuum‐evaporated Cs 2 CO 3 as EIL. Such improvements can also be observed in inverted organic light‐emitting diodes. The device with [(H 3 O)Zn(HCOO) 3 ] ∞ s‐EIL demonstrates an operating voltage of 6.8 V at 1000 cd m −2 , much lower than that with Cs 2 CO 3 EIL (8.4 V). And the power efficiency is increased about 18%. The enhanced electron injection property of [(H 3 O)Zn(HCOO) 3 ] ∞ ‐modified indium–tin oxide (ITO) is attributed to its reduced work function compared to bare ITO, which is confirmed by ultraviolet photoelectron spectroscopy analysis. This approach is anticipated to be applied in other optoelectronic devices for efficient electron injection.