Single-Layer Light-Emitting Diodes Using Organometallic Halide Perovskite/Ionic-Conducting Polymer Composite

Abstract

Single-layer LEDs were developed using a composite thin film of organometal halide perovskite (Pero) and poly (ethylene oxide) (PEO). Single-layer Pero LEDs have a device structure that resembles “bottom electrode (ITO)/Pero-PEO/top electrode (In/Ga or Au)”. Green emission LEDs with methylammonium lead bromide (bromide-Pero) and PEO composite thin films exhibit a low turn-on voltage of about 2.8-3.1V (defined at 1 cd m−2 luminance), a maximum luminance of 4064 cd m−2 and a moderate maximum current efficiency of about 0.24-0.74 cd A−1. Blue and red emission LEDs have also been fabricated using Cl/Br or Br/I alloyed Pero-PEO composite thin films.

What is claimed is: 
     
         1 . A method for producing a single layer thin film optoelectronic device, the method comprising:
 providing an organometal halide perovskite (Pero) precursor;   contacting an ionic-conducting polymer (ICP) and the Pero precursor to form a Pero-ICP precursor;   coating a substrate with the Pero-ICP precursor to form a Pero-ICP composite layer; and   annealing the Pero-ICP composite layer.   
     
     
         2 . The method of  claim 1 , wherein the Pero precursor comprises a mixture of AX and BX, where A is a cation, B is a metal, and X is a halide ion. 
     
     
         3 . The method of  claim 2 , wherein A comprises methylammonium (CH 3 NH 3 ), formamidinium (NH 2 CHNH 2 ), cesium (Cs), or a mixture thereof. 
     
     
         4 . The method of  claim 2 , wherein B comprises lead (Pb), tin (Sn), germanium (Ge), or a mixture thereof. 
     
     
         5 . The method of  claim 2 , wherein X comprises fluoride (F − ), chloride (Cl − ), bromide (Br − ), iodide (I − ), astatide (At − ), or a mixture thereof. 
     
     
         6 . The method of  claim 2 , wherein forming the Pero precursor comprises mixing AX and BX at a ratio of about 0.5 mole AX to 1 mole BX. 
     
     
         7 . The method of  claim 6 , wherein the Pero precursor further comprises dimethylformamide or dimethylsulfoxide. 
     
     
         8 . The method of  claim 1 , wherein the ICP comprises oligomers or polymers of ethylene oxide, a polysaccharide polymer, or a conjugated polymer. 
     
     
         9 . The method of  claim 1 , wherein the weight percent of the ICP relative to the weight of the Pero in the Pero-ICP precursor ranges from about 5 percent to about 75 percent. 
     
     
         10 . The method of  claim 1 , wherein the Pero-ICP composite layer comprises methylammonium lead halide (CH 3 NH 3 PbX 3 ), formamidinium lead halide (NH 2 CHNH 2 PbX 3 ), cesium lead halide (CsPbX 3 ), or a mixture thereof, wherein X is a halide. 
     
     
         11 . The method of  claim 1 , wherein coating the substrate comprises spin coating the organometal halide perovskite precursor onto the substrate. 
     
     
         12 . The method of  claim 11 , wherein a duration of the spin coating step comprises about 60 seconds. 
     
     
         13 . The method of  claim 1 , wherein annealing the Pero-ICP composite layer comprises heating the Pero-ICP composite layer to about 60° C. for 3 minutes. 
     
     
         14 . A method for producing a single layer thin film optoelectronic device, comprising:
 forming an organometal halide perovskite (Pero) precursor by (i) dissolving methylammonium chloride (CH 3 NH 3 Cl) and lead chloride (PbCl 2 ) in dimethylsulfoxide, or (ii) dissolving methylammonium bromide (CH 3 NH 3 Br) and lead bromide (PbBr 2 ) in N,N-dimethylformamide, or (iii) dissolving methylammonium iodide (CH 3 NH 3 I) and lead iodide (PbI 2 ) in N,N-dimethylformamide;   contacting poly(etheylene oxide) polymer (PEO) with the Pero precursor to form a Pero-PEO precursor;   coating a substrate with the Pero-PEO precursor to form a layer of Pero-PEO composite on the substrate; and   annealing the Pero-PEO composite layer.   
     
     
         15 . The method of  claim 14 , wherein the Pero precursor comprises a molar ratio of lead chloride to methylammonium chloride of about 1:1.5, a molar ratio of lead bromide to methylammonium bromide of about 1:1.5, or a molar ratio of lead iodide to methyammonium iodide of about 1:1.5. 
     
     
         16 . The method of  claim 14 , wherein the coating the substrate comprises spin coating the Pero-PEO precursor onto the substrate.