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 7/13 (Fri) Prof. Dong Ryeol Whang (Johannes Kepler University Linz, Austria) ADMINI 2018.07.09 64
Notice 6/5 (Tue) Prof. Sunghwan Lee (Baylor University) ADMINI 2018.06.05 270
Notice 5/29 (Tue) Prof. Sang Ho Oh (Yonsei Univ. College of Medicine) ADMINI 2018.05.29 270
Notice 5/15 (Tue) Prof. Myung Gil Kim (Dept. of Chemistry, Chung-Ang Univ.) ADMINI 2018.05.15 489
245 11/24 (Fri) Takashi NOGUCH (University of the Ryukyus) ADMINI 2017.11.23 815
244 11/21 (Tue) Dr. Young Ki Lee (ETRI) file ADMINI 2017.11.20 1006
243 11/22 (Wed) Prof. Sung Hoon Kang (Johns Hopkins University) file ADMINI 2017.11.20 1238
242 11/21 (Tue) Dr. Byoung Koun Min, (KIST) ADMINI 2017.11.17 1368
241 11/13 (Mon) Dr. Hans Aage Hiuler (Danish Power System) ADMINI 2017.11.10 728
240 11/13 (Mon) Prof. Jens Oluf Jensen (Technical University of Denmark) ADMINI 2017.11.10 710
239 11/14 (Tue) Prof. Jae-Byum Chang (Sungkyunkwan Univ) ADMINI 2017.11.10 723
238 11/7 (Tue) Prof. Su-Mi Hur (Chonnam National University) ADMINI 2017.11.05 548
237 10/31 (Tue) Director Jang Sae Young (Samsung Electronics) ADMINI 2017.10.26 554
236 11/6 (Mon) Prof. Redouane Borsali (Grenoble Alpes University) ADMINI 2017.10.26 654
235 11/6 ~ 7 Prof. Erik Luijten (Northwestern University) file ADMINI 2017.10.25 610
234 10/23 ~ 24 Prof. Paul C. McIntyre (Stanford University) file ADMINI 2017.10.25 536
233 10/24 (Tue) Prof. Sun-Jae Kim (Sejong, Univ) ADMINI 2017.10.20 968
232 10/19 (Thu) Prof. Sang Cheol, Jung (Suncheon University) ADMINI 2017.10.18 1310
231 10/10 (Tue) Dr. Joo Choi (POSCO) ADMINI 2017.09.29 2214
» 9/26 (Tue) Prof. Tae-Woo Lee (Seoul National University) ADMINI 2017.09.22 1124
229 9/19 (Tue) Representative Sang Min Lee (Congressman) ADMINI 2017.09.15 1207
228 9/12 (Tue) Monika Fleischer(Eberhard Karls University Tübingen) ADMINI 2017.09.14 813
227 2017 The Fall Semester Seminar file ADMINI 2017.09.08 2951
226 9/12 (Tue) Prof. Pil Jin, Yoo (Sungkyunkwan Univ) ADMINI 2017.09.08 1340