Grant: Discovery Grants Program - Individual

Despite its proven maturity, the power conversion efficiency of silicon solar cell technology is lower than the fundamental Shockley-Queisser (SQ) limit of 33 %, in addition to their relatively high cost. In this research program, the short-term objective is to develop a highly efficient but low-cost photovoltaic technology. We aim to break the SQ limit and develop a new generation of solar cells based on a novel hot carrier idea. A hot carrier is a photogenerated electron or hole with excess energy resulting from the energy difference between the incident photon and the band gap of solar absorbers. However, the hot carriers rapidly lose their excess energy in less than a picosecond due to their interactions with phonons. Thus, the ultrashort lifetime of hot carriers is the main bottleneck preventing us from achieving record efficiency since the hot carriers cannot be readily collected as a photocurrent in a solar cell. Emergent inorganic perovskite nanocrystals CsPbX3 (X=Cl, Br, I) are promising candidates of hot carrier solar absorber because of their unique quantum confinement effect, which gives rise to discrete energy levels that prolong the hot carrier lifetime. In addition, their band gap can be uniquely tuned by the nanocrystal size. Moreover, they can be synthesized under an ambient environment and processed by solution processing, leading to significant cost reduction. In this research program, we will focus on the CsPbX3 perovskite nanocrystals as hot carrier solar absorbers, and systematically address the photovoltaic efficiency challenge from three fundamental areas including reaction dynamics, surface chemistry, and charge carrier transport dynamics, which correspond to three research objectives including 1) constructing stable device structures, 2) enhancing the perovskite solar absorber electrical property, 3) identifying the hot carrier transport dynamics. This research program also aligns well with my long-term vision to understand the charge carrier transport dynamics in advanced materials, leading to a new generation of device applications in renewable energy and optical quantum communication. Our work will profoundly impact the socio-economic and environmental benefits by evolving the fields of renewable energy, optoelectronics, and advanced materials. This work will accelerate the development of a low-cost photovoltaic technology and advance our knowledge of nanocrystal reaction dynamics, surface chemistry, and carrier transport dynamics. This fundamental research bridges the gap between the foundational carrier dynamic with novel device application. This interdisciplinary research will provide extensive HQP training skills such as nanomaterials synthesis, ultrafast laser operation, thin film morphology characterization, and solar cell fabrication. This work will foster a unique research environment for HQP and train a diverse student population including graduate and undergraduate students, and underrepresented groups.