March 24
@
12:00 PM
–
1:00 PM
Enabling Perovskite Semiconductors for a Brighter, Safer, and Efficient World
Abstract:
Light-emitting diodes (LEDs) have enabled critical functionality across a range of applications, including solid-state lighting, displays, water purification, 3D printing, sensing, and more. Metal halide perovskite semiconductors are promising candidates for next-generation optoelectronic devices, including LEDs, due to their bandgap tunability, sharp color purity, and inexpensive processing. In this seminar, I will present my research towards optimizing the performance of emissive perovskite semiconductors in both the visible and ultraviolet (UV) spectrum. Focusing first on the visible spectrum, by replacing a portion of the lead with manganese and introducing tris(4-fluorophenyl)phosphine oxide (TFPPO) as an additive in organic-inorganic hybrid quasi-bulk perovskite thin films, we can achieve bright and efficient perovskite LEDs (PeLEDs). However, while the TFPPO additive boosts green Mn 2+ -doped PeLED efficiency, it also worsens its device stability. By utilizing repeated electrical scans and time-resolved photoluminescence measurements, we systematically study this efficiency-stability trade-off. Next, we employ emissive 2D lead halide perovskites to push light emission towards the UV spectrum. By engineering the films and corresponding device architectures, we can fabricate both 408 nm violet- emitting and 399 nm UV-emitting PeLEDs. Furthermore, to achieve deeper UV light emission, one must consider other materials beyond 2D lead halide perovskites. By investigating lead-free rare earth element-based perovskite materials, we show that cerium-based perovskite films can demonstrate 367 nm photoluminescent emission paving the way for deeper UV-emitting PeLEDs. Lastly, by combining organic spacer cations and europium halides, we showcase bright, lead-free perovskite nanoplatelets and enable new non-toxic pathways for both deep blue and violet light emission. Finally, I will share my vision for engineering next-generation perovskite optoelectronic and electronic devices for applications in displays, public health, quantum computing, microelectronics, and beyond.
Bio:
Sebastian Fernández is a Stanford Diversifying Academia, Recruiting Excellence (DARE) Fellow, U.S. Department of Energy IBUILD Fellow, P. Michael Farmwald Stanford Graduate Fellow in Science & Engineering, GEM Fellow, and Ph.D. Candidate in the Department of Electrical Engineering at Stanford University. Previously, Sebastian received his B.S. in Electrical Engineering with a minor in Mathematics from the Georgia Institute of Technology in 2019 and M.S. in Electrical Engineering from Stanford University in 2021.
Sebastian Fernandez
Sebastian is passionate about teaching and has led his own Differential Equations recitation five times as a Georgia Tech undergraduate as well as uploading his lectures on YouTube and amassing over 350,000 views. Additionally, Sebastian has broadened participation within engineering by serving as the vice-chair of the Stanford School of Engineering’s Dean’s Graduate Student Advisory Council and co-founding the Stanford Engineering Research Introductions Organization, which he leads as president to prepare underrepresented undergraduate students for graduate school. Sebastian’s contributions have been recognized with several honors, including the 2024 Winner of the University of Washington Chemical Engineering Distinguished Young Scholars Seminar (DYSS) Series, University of California, Berkeley Electrical Engineering & Computer Sciences BETR Solid State Technology and Devices Seminar Speaker, University of Illinois Urbana-Champaign Materials Science & Engineering Hard Materials Seminar Speaker, Rising Star in Materials Science and Engineering (MIT, Stanford, UIUC, and CMU), Northwestern University Materials Science and Engineering Future Leader and Department Seminar Speaker, University of Wisconsin-Madison WiscProf Selectee, NextProf Nexus Selectee (UC Berkeley, Georgia Tech, and UMichigan), Cadence LatinX Student in Technology Scholarship Winner, and the Georgia Institute of Technology Undergraduate Teaching Assistant of the Year Winner.