Princeton University

School of Engineering & Applied Science

Molecular Doping of Organic Semiconductors

Xin Lin
Prof. Antoine Kahn
Engineering Quad J401
Monday, March 26, 2018 - 1:00pm to 2:00pm

Molecular doping of organic semiconductors is becoming exceedingly important and has led to significant commercial developments in organic electronics, since it allows to overcome performance deficiencies and material limitations.  Increasing attention has recently been placed on using very low concentrations of dopants to eliminate the effect of defects in organic semiconductors, in order to achieve overall better device performance. However, direct spectroscopic observations and quantitative analyses have not been done yet to study the impact of dopants on the density of states of organic semiconductors. In my Ph.D. study, by using a combination of electron spectroscopy and carrier transport measurements, the density of states in an organic semiconductor was investigated, upon the introduction of minute amounts of a p-dopant.  Another challenge in the field of organic electronics is n-type doping, which means adding electrons to the organic semiconductor by using the n-dopant. Air-stable molecular n-dopants suitable for a special class of materials, which are exceedingly important in a range of applications, are essentially non-existent. We demonstrated a major advance to n-dope these difficult-to-dope organic semiconductors using cleavable air-stable dimeric dopants accompanied with photo-activation. High-efficiency organic light-emitting diodes are fabricated by using materials doped in this manner. Our strategy thus enables a new paradigm to improve conductivity in these organic semiconductors and overcome their restrictions on the choice of electrode, giving more freedom to device design and optimization.“