Methods to protect and recover work function of air exposed transition metal oxide thin films

Irfan Irfan; Chenggong Wang; Alexander James Turinske; Yongli Gao

doi:10.1117/12.927812

13 September 2012 Methods to protect and recover work function of air exposed transition metal oxide thin films

Irfan Irfan, Chenggong Wang, Alexander James Turinske, Yongli Gao

Proceedings Volume 8476, Organic Light Emitting Materials and Devices XVI; 847616 (2012) https://doi.org/10.1117/12.927812
Event: SPIE Organic Photonics + Electronics, 2012, San Diego, California, United States

Abstract

Insertion of high work function (WF) transition metal oxide (TMO) layers between the anode and the hole transport layer is established to substantially enhance the performance of organic light emitting diodes (OLED). The high WF of transition metal oxide layer has been demonstrated to be the most crucial for the enhancement. The WF of a TMO layer decreases substantially with air exposure, and noticeably by the ambient even inside a low vacuum system. In the present work we discuss various methods to protect and recover the high WF after a TMO thin film has been exposed to air. We report covering a thin organic layer on top of MoO_x to protect the high work function. We found that a thin layer of 1-2 nm organic layer was sufficient to protect the work function of MoO_x thin film underneath. We further report methods to recover already decreased TMO WF due to air exposure. We performed oxygen plasma cleaning of air exposed MoO_x film and found out that oxygen plasma could substantially recover the WF of as deposited MoO_x film. We also performed annealing of air exposed MoO_x film inside an ultra high vacuum system and observed a thin layer of oxygenrich adsorbate layer, which desorbed upon annealing that in turn substantially recovered the MoO_x WF. We discuss the vacuum annealing and the effect of resulting surface on the interface energy level alignment.

Citation Download Citation

Irfan Irfan, Chenggong Wang, Alexander James Turinske, and Yongli Gao "Methods to protect and recover work function of air exposed transition metal oxide thin films", Proc. SPIE 8476, Organic Light Emitting Materials and Devices XVI, 847616 (13 September 2012); https://doi.org/10.1117/12.927812

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available