All‐Inorganic CsPbI₃ Perovskite Phase‐Stabilized by Poly(ethylene oxide) for Red‐Light‐Emitting Diodes

Abstract

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.

All‐Inorganic CsPbX3 Perovskite Solar Cells: Progress and Prospects

“…[17] ThePCEs of cells reported in these studies (Ref. [118] dealt with LEDs) were mostly high, with V OC % 1.1 Vi na ll cases and PCEs of 10.6 %, [117] 11.4 %, [119] 13.5 %, [120] 6.8 % [121] and 16.3 %, [17] all stabilized PCEs except for Refs. [117,121] which were rfPCE.…”

“…There are an umber of studies describing the effects of adsorption of organic species on CsPbI 3 crystal surfaces with the main reason being to stabilize one of the black phases. Other effects of such adsorption are reduction in crystal size (which may be the cause,i np art or in whole for the stabilization) or passivation of surface traps.Different organic species have been used for this purpose:polyvinylpyrollidone (PVP,shown in Figure 6b), [117] polyethylene oxide (PEO), [118] sulfobetaine zwitterions (shown in Figure 6c), [119] phenyltrimethylammonium bromide (PTABr), [17] phenylethylammonium cation (PEA) [120] and diethylenetriamine (DETA). [121] In all but Refs.…”

Anorganische CsPbX3‐Perowskit‐Solarzellen: Fortschritte und Perspektiven

“…Verschiedene organische Spezies wurden zu diesem Zweck eingesetzt:P olyvinylpyrrolidon (PVP) (Abbildung 6b), [117] Polyethylenoxid (PEO), [118] Sulfobetain-Zwitterionen (Abbildung 6c), [119] Phenyltrimethylammoniumbromid (PTABr), [17] Phenylethylammoniumkation (PEA) [120] und Diethylentriamin (DETA). Andere Auswirkungen solcher Adsorptionen sind die Verringerung der Kristallgrçße (was ganz oder teilweise die Ursache fürd ie Stabilisierung sein kann) oder die Passivierung von Oberflächenfallen.…”

“…Ein Wert n beziffert die Anzahl der Oktaederschichten bezogen auf die Grçße des 3D-Teils vor der Separierung durch das organische A-Kation. Durch Veränderung von n kçnnen daher Eigenschaften zwischen reinen 3D-HaPs (n!1)und reinen 2D-HaPs (n = 1) ausbalanciert werden, insbesondere eine verbesserte [117] Polyethylenoxid (PEO), [118] Sulfobetain-Zwitterionen (Abbildung 6c), [119] Phenyltrimethylammoniumbromid (PTABr), [17] Phenylethylammoniumkation (PEA) [120] und Diethylentriamin (DETA). In allen Fällen -a ußer in Lit.…”

“…In allen Fällen -a ußer in Lit. [17] Die organischen Spezies erhçhten die Ladungsträgerlebensdauer [117,118] sowie die Zellleistung. [120,121] Bei Behandlung mit PTABr kam es zu einem gewissen Br/I-Austausch, der sich auch auf die Phasenstabilitäta uswirken kçnnte.A llerdings war die Menge an Br in den Filmen sehr gering und verursachte eine spektrale Blauverschiebung von lediglich < 5nm( entsprechend < 2% des gesamten Halogenids basierend auf einem homogenen HaP).…”