Despite the excellent photoelectronic properties of the all-inorganic cesium lead iodide (CsPbI3) perovskite, which does not contain volatile and hygroscopic organic components, only a few CsPbI3 devices are developed mainly owing to the frequent formation of an undesirable yellow δ-phase at room temperature. Herein, it is demonstrated that a small quantity of poly(ethylene oxide) (PEO) added to the precursor solution effectively inhibits the formation of the yellow δ-phase during film preparation, and promotes the development of a black α-phase at a low crystallization temperature. A systematic study reveals that a thin, dense, pinhole-free CsPbI3 film is produced in the α-phase and is stabilized with PEO that effectively reduces the grain size during crystallization. A thin α-phase CsPbI3 film with excellent photoluminescence is successfully employed in a light-emitting diode with an inverted configuration of glass substrate/indium tin oxide/zinc oxide/poly(ethyleneimine)/α-CsPbI3/poly(4-butylphenyl-diphenyl-amine)/WO3/Al, yielding the characteristic red emission of the perovskite film at 695 nm with brightness, external quantum efficiency, and emission band width of ≈101 cd m−2, 1.12%, and 32 nm, respectively.
Bibliographical noteFunding Information:
This research was supported by a grant from the National Research Foundation of Korea (NRF) funded by the Korean government (MEST) (No. 2017R1A2A1A05001160), the Ministry of Science, ICT Future Planning (MSIP) of Korea under contracts (No. NRF-2012M3A6A7054861, the Global Frontier R&D Program on Center for Multiscale Energy System), and the Global Ph.D. Fellowship Program funded by the Ministry of Education (NRF-2013H1A2A1033524). This work is based on a work supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under the Industrial Technology Innovation Program (No. 10063274).
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics