Perovskite Semiconductors for Opto-Electronic Device and Radiation Detector
Los Alamos National Lab
Abstract: Perovskite semiconductors are recognized as emergent materials for high performance opto-electronics such as photovoltaic and light emitting devices. For example, the progress in the perovskite solar cell community is unprecedented. The power conversion efficiency of a single junction perovskite solar cell has hit 23%  and that for the tandem cells is boosted up to 25% . In this seminar, I will introduce the basic structure and semiconducting properties of hybrid perovskite materials in both 2D and 3D structures and their applications in electronic devices. Specifically, I will correlate the material structure and properties to the device operational principles. Firstly, photovoltaic device operation will be taken as an example. Our team have developed a solution approach to produce highly crystalline 3D and 2D perovskite thin films for photovoltaic device operation [3-4]. We also found the device stability is related to the structure and their dynamics triggered by light . Therefore, by organic molecule engineering, we were able to obtain stabilized cubic phase perovskites that output 20% power conversion efficiency when being fabricated into a solar cell. The performance was stable under constant operational conditions. We further probed the structure and dynamics triggered by light and observed a lattice change triggered light, which has a direct impact on the electronic properties of the materials . Secondly, I will introduce solid state radiation detectors using perovskite single crystals as new application. Because of the presence of the heavy elements in the material, the perovskite crystals can be potentially used for the detection of high energy photons (e.g. X-ray or Gamma-ray photons). In our study, we demonstrate a perovskite detector as gamma-ray photon counter. By putting high work function metal electrodes, we successfully blocked out the dark noise from electronic impurities and obtain electronic pulses correspond to gamma-ray photon interactions. I will also cover the operational physics of the gamma-ray photon counter and discuss the path forward to the performance improvement by structure design.
1. Nie et al, Science 360, 67-70 (2018)
2. Nie et al, Nature 536, 312 (2016)
3. Nie et al, Nature communications 7, 11574 (2016)
4. Nie et al, Science 347, 522-525 (2015)
Bio : Dr. Wanyi Nie is a staff scientist in Material Physics and Application Division (MPA) at Los Alamos National Laboratory (LANL). Dr. Nie graduated from Wake Forest University with a Ph.D. degree in physics in late 2012. Her Ph.D. thesis was on the optimization of organic photovoltaics. She later joined LANL with prestigious LANL director postdoc fellowship from 2013 to 2016 working on interfacial charge transfer states of organic electronics. Since 2016, she has been working as a staff scientist at LANL continuing to develop hybrid semiconductors, such as hybrid perovskites and metal organics, for opto-electronic devices. She is also an affiliate scientist at Center of Integrated Nanotechnology at LANL, a DOE user facility. Wanyi serves as reviewer for peer reviewed journals, such as Nature, Nature Communications, Science Advances, JACS, Advanced Materials etc; and she also serves as reviewer for several funding agent (LANL Laboratory Directed Research Direction Office, DOE office of science, and other international grant offices). Homepage: https://wnieslab.wixsite.com/wnie
Refreshments will be served afterwards in the PandA Café.
Thursday, September 12, 2019 at 4:00pm to 5:00pm
Kinard Laboratory of Physics, G01 Kinard Lab
140 Delta Epsilon Ct., Clemson, SC 29634, USA