Occurring monthly during the academic year, the 2DCC Webinars present new technical scientific news from within the 2DCC facility and the broader scientific community, as well as, broader topics such as science related to diversity. The webinars are free with an online registration. The slides with voice-over for the 2016 webinars, 2017 webinars, 2018 webinars and 2019 webinars are available by following the links in the left menu. Information regarding the next scheduled webinar is listed below.
DATE: Tuesday, March 24, 2020
TIME: 12:00 pm - 1:00 pm Eastern
Title: Photovoltaics with Van der Waals Semiconductors: Promising or Pipe Dream?
High efficiency inorganic photovoltaic materials (e.g., Si, GaAs and GaInP) can achieve maximum above-bandgap absorption as well as carrier-selective charge collection at the cell operating point. But thin film photovoltaic absorbers have lacked the ability to maximize absorption and efficient carrier collection, concurrently often due to due to surface and interface recombination effects. In contrast, Van der Waals semiconductors have naturally passivated surfaces with electronically active edges that allows retention of high electronic quality down-to the atomically thin limit. This presents interesting opportunities for remote power and applications that require high-specific power in place of cost or efficiency. This webinar will focus on a review of advances in photovoltaics based on 2D semiconductors to date for the first part
In the second part, I will show some of our own results in this space which have been dedicated to systematically address the three major engineering challenges for efficient photovoltaics: 1. Light absorption 2. Carrier collection 3. Band alignments. I will present our experimental demonstration of near-unity light confinement in ultrathin (< 15 nm) Van der Waals semiconductors (MoS2, WS2 and WSe2) leading to nearly perfect absorption.1 I will further present the fabrication and performance of our, broadband absorbing, heterostructure photovoltaic devices using sub-15 nm TMDCs as the active layers, with record high quantum efficiencies. 2 I will then present ongoing work on addressing the key remaining challenges for application of 2D materials and their heterostructures in high efficiency photovoltaics 3 which entails engineering of interfaces and open-circuit voltage 4 as well as on going work on novel materials and light trapping 5 in monolayers. I will conclude by giving a broad perspective of future work on 2D materials from fundamental science to applications.
Dr. Deep Jariwala
Assistant Professor, Electrical and Systems Engineering
Materials Science and Engineering University of Pennsylvania