EAGER: Electrically pumped transient charge-carrier dynamics of metal halide perovskite light-emitting diodes

Princeton University, Princeton NJ

Investigators

Abstract

Metal halide perovskite light-emitting diodes (PeLEDs) hold potential for a new generation of display and lighting technology, featuring high color quality, energy efficiency and low manufacturing cost. Additionally, perovskites are deposited from solution, meaning that they can be deposited on virtually any substrate, including silicon. However, the slow operation speed of PeLEDs limits their potential for a wider scope of applications, such as interchip and intrachip optical communications, which are dominated by more expensive technologies using III-V semiconductors. In this project, the PI proposes to study transient charge-carrier dynamics of PeLEDs under ultrashort electrical excitation. If successful, the proposed investigation will advance the understanding of the intrinsic speed limitations in these materials, and can begin in earnest for less well developed aspects of halide perovskite optoelectronic applications, such as in optical communications integrated on-chip. Currently, such applications are restricted due to unknowns regarding perovskite LED switching speeds, and this proposed project will fill these knowledge gaps. The research will strengthen technological leadership of the U.S. and prepare the next generation of STEM graduates, including women and underrepresented groups, to follow a STEM career. The PI will continue to engage with the public and students, and is particularly involved in active learning activities to establish role models across generational gaps. At the undergraduate and graduate level, the PI will, via lectures, practical labs, research and courses, stress applications and the benefits of science on society and include guest lectures in order to inspire a new generation of STEM students and allow students to see the rewards of a STEM career. Probing transient charge-carrier dynamics in real devices is important to understand their operation mechanisms. However, reported studies on charge-carrier dynamics so far, as far as can be understood, have been constrained by optical pumping. No studies have ever been conducted to probe the transient charge carrier dynamics under electrical excitation, which is closer to the real device operation conditions. On the other hand, electrical excitation is considerably distinct from optical pumping, and this likely is due to interface or bulk electrochemical processes that couple transport equations with chemical processes. The proposed study will investigate transient charge-carrier dynamics of PeLEDs under ultrashort electrical excitation and investigate how additional electrochemical processes will cause the differences between optical and electrical pumping with respect to recombination processes. Then, the PI will investigate and understand how the various perovskite compositions will influence the transient charge-carrier dynamics under electrical pumping, and disclose dominant factors governing the transient device response and make faster PeLEDs possible. Two scientific goals that will allow for future applications are: 1) advancing the understanding of the intrinsic speed limitations in PeLEDs; 2) a better appreciation for differences between optical and electrical pumping with respect to recombination processes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.