Spacer Cation Alloying in Ruddlesden-Popper Perovskites for Efficient Red Light-Emitting Diodes with Precisely Tunable Wavelengths

Abstract

Perovskite light-emitting diodes (PeLEDs) have recently shown significant progress with external quantum efficiencies (EQEs) exceeding 20%. However, PeLEDs with pure-red (620-660 nm) light emission, an essential part for full-color displays, remain a great challenge. Herein, a general approach of spacer cation alloying is employed in Ruddlesden-Popper perovskites (RPPs) for efficient red PeLEDs with precisely tunable wavelengths. By simply tuning the alloying ratio of dual spacer cations, the thickness distribution of quantum wells in the RPP films can be precisely modulated without deteriorating their charge-transport ability and energy funneling processes. Consequently, efficient PeLEDs with tunable emissions between pure red (626 nm) and deep red (671 nm) are achieved with peak EQEs up to 11.5%, representing the highest values among RPP-based pure-red PeLEDs. This work opens a new route for color tuning, which will spur future developments of pure-red or even pure-blue PeLEDs with high performance. ; Funding Agencies|ERCEuropean Research Council (ERC)European Commission [717026]; Swedish Research Council VRSwedish Research Council [2018-07109]; Swedish Foundation for International Cooperation in Research and Higher Education [CH2018-7736]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Nanyang Technological UniversityNanyang Technological University [M4080514]; Ministry of Education, SingaporeMinistry of Education, Singapore [MOE2019-T2-1-006, MOE-T2EP50120-0004]; National Research Foundation (NRF), SingaporeNational Research Foundation, Singapore [NRF-NRFI2018-04]; NSFCNational Natural Science Foundation of China (NSFC) [61774077]; Key Projects of Joint Fund of Basic and Applied Basic Research Fund of Guangdong Province [2019B1515120073, 2019B090921002, 2020A1414010036]; Guangzhou Key laboratory of Vacuum Coating Technologies and New Energy Materials Open Projects Fund [KFVE20200006]; China Postdoctoral Science FoundationChina Postdoctoral Science Foundation [2020M673055]; Science and Technology Planning Project of Guangzhou, China [201605030008]; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities [21621008]