신소재공학과

Seminar

Date 20170926 

■ Title:  Next LEDs: Metal Halide Perovskite Light-Emitting Diodes


■ Speaker: Prof. Tae-Woo Lee (Dept. of MSE, Seoul National University) 

 

■ Date and time: 26th of September, (Tue) 16:00

 

■ Venue: Applied Engineering Dpt. Bd W1 Multimedia Lecture Hall (1st Floor)

 

 Host : Prof. Duk young Jeon

  

 Abstract : Metal halide perovskites are emerging high color-purity emitters with low material cost. However, low electroluminescence (EL) efficiency at room temperature is a challenge that should be overcome. Here, we present efficient perovskite light-emitting diodes (PeLEDs) using various strategies to overcome the EL efficiency limitations where the perovskite layers are in forms of (1) 3D crystal structures, (2) quasi-2D crystal structures and (3) nanoparticles (NPs). First, to improve EL efficiency of PeLEDs based on 3D crystal structures, we introduced a self-organized buffer hole injection layer to reduce the hole injection barrier and block the exciton quenching at the interface. The high-efficiency methylammonium lead bromide (MAPbBr3) and CsPbBr3 PeLEDs were realized based on the buffer hole injection layers and the temperature dependence of EL in the CsPbBr3 PeLEDs was systematically investigated and related with ion migration, EL quenching pathways and electron-phonon coupling. Furthermore, we found that the formation of metallic lead atoms causes strong exciton quenching, and it was prevented by finely increasing the molar proportion of MABr in MAPbBr3 solution. Also, we suggest that the efficiency in PeLEDs can be increased by decreasing MAPbBr3 grain sizes and consequently improving uniformity and coverage of MAPbBr3 layers. Using these strategies, a high-efficiency PeLEDs was realized (current efficiency = 42.9 cd/A). High-efficiency flexible MAPbBrPeLEDs based on graphene anode were also developed for the first time. Chemically inert graphene avoids quenching of excitons by diffused metal atom species from indium tin oxide. Second, quasi-2D perovskites were studied because of the advantages of quasi-2D perovskites such as the enhancement of film quality, exciton confinement and reduced trap density, and quasi-2D PeLEDs with high efficiency and brightness were demonstrated. Finally, perovskite NPs were studied because they can show high luminescence efficiency and high color-purity in both solution states and film states, and high efficiency PeLEDs based on MAPbBr3 and formaminidium lead bromide (FAPbBr3) NPs were also fabricated.

No. Subject Author Date Views
Notice 11/21 (Tue) Dr. Young Ki Lee (ETRI) ADMINI 2017.11.20 134
Notice 11/22 (Wed) Prof. Sung Hoon Kang (Johns Hopkins University) ADMINI 2017.11.20 141
Notice 11/21 (Tue) Dr. Byoung Koun Min, (KIST) ADMINI 2017.11.17 298
Notice 2017 The Fall Semester Seminar ADMINI 2017.09.08 1420
240 11/13 (Mon) Dr. Hans Aage Hiuler (Danish Power System) ADMINI 2017.11.10 403
239 11/13 (Mon) Prof. Jens Oluf Jensen (Technical University of Denmark) ADMINI 2017.11.10 381
238 11/14 (Tue) Prof. Jae-Byum Chang (Sungkyunkwan Univ) ADMINI 2017.11.10 381
237 11/7 (Tue) Prof. Su-Mi Hur (Chonnam National University) ADMINI 2017.11.05 278
236 10/31 (Tue) Director Jang Sae Young (Samsung Electronics) ADMINI 2017.10.26 290
235 11/6 (Mon) Prof. Redouane Borsali (Grenoble Alpes University) ADMINI 2017.10.26 393
234 11/6 ~ 7 Prof. Erik Luijten (Northwestern University) file ADMINI 2017.10.25 375
233 10/23 ~ 24 Prof. Paul C. McIntyre (Stanford University) file ADMINI 2017.10.25 308
232 10/24 (Tue) Prof. Sun-Jae Kim (Sejong, Univ) ADMINI 2017.10.20 398
231 10/19 (Thu) Prof. Sang Cheol, Jung (Suncheon University) ADMINI 2017.10.18 480
230 10/10 (Tue) Dr. Joo Choi (POSCO) ADMINI 2017.09.29 1119
» 9/26 (Tue) Prof. Tae-Woo Lee (Seoul National University) ADMINI 2017.09.22 781
228 9/19 (Tue) Representative Sang Min Lee (Congressman) ADMINI 2017.09.15 772
227 9/12 (Tue) Monika Fleischer(Eberhard Karls University Tübingen) ADMINI 2017.09.14 535
226 9/12 (Tue) Prof. Pil Jin, Yoo (Sungkyunkwan Univ) ADMINI 2017.09.08 663
225 9/11 (Mon) Won Joon, Cho (Lawrence Berkeley National Lab, Berkeley) ADMINI 2017.09.06 749