Enhanced performance in fluorene-free organometal halide perovskite light-emitting diodes using tunable, low electron affinity oxide electron injectors.

Guangru Li,Neil C. Greenham,May‐Ling Lai,Dan Credgington,Robert L. Z. Hoye,Kevin P. Musselman,Zhi‐Kuang Tan,Richard H. Friend,Matthew R. Chua,Judith L. MacManus‐Driscoll

doi:10.1002/adma.201405044

Abstract

Fluorene-free perovskite light-emitting diodes (LEDs) with low turn-on voltages, higher luminance and sharp, color-pure electroluminescence are obtained by replacing the F8 electron injector with ZnO, which is directly deposited onto the CH3NH3PbBr3 perovskite using spatial atmospheric atomic layer deposition. The electron injection barrier can also be reduced by decreasing the ZnO electron affinity through Mg incorporation, leading to lower turn-on voltages.

Highlights

Organometal halide perovskites used in solar cells have demonstrated an astonishing increase in power conversion efficiency from 4% in 2009 to 19.3% in 2014,[8] while their high photoluminescence quantum efficiency has allowed the first demonstrations of optically pumped lasing.[9,10] More recently, the demonstration of room temperature electroluminescence from this material promises a bright future for perovskite light-emitting diodes (LEDs) (PeLED) technology.[4]
Spray pyrolysis, which is the common method for producing metal oxides in hybrid LEDs, requires deposition temperatures >350 °C
This renders it incompatible with flexible polymer substrates or direct deposition onto perovskites.[3,18,19]. We overcame these limitations by using spatial atmospheric atomic layer-deposited (SAALD) ZnO films, formed at only 60 °C and deposited directly onto green-emitting methylammonium lead tri-bromide (CH3NH3PbBr3) perovskite

Summary

Introduction

Organometal halide perovskites used in solar cells have demonstrated an astonishing increase in power conversion efficiency from 4% in 2009 to 19.3% in 2014,[8] while their high photoluminescence quantum efficiency has allowed the first demonstrations of optically pumped lasing.[9,10] More recently, the demonstration of room temperature electroluminescence from this material promises a bright future for perovskite LED (PeLED) technology.[4]. To show that our tunable metal oxide is high quality and can be used in efficient LEDs, we applied this electron injector to mature polymer LED (PLED) technology, demonstrating luminous efficiencies comparable to or exceeding previous records with hybrid green F8BT and blue aryl-F8:0.5 wt% TFB devices, 1414 wileyonlinelibrary.com

Results

Conclusion