CISS Effects in Photoinduced Electron Transfer from Semiconductor Nanocrystals

In this project, Prof. Tianquan (Tim) Lian and a team of graduate and undergraduate students at University of Pennsylvania will develop quantum confined nanocrystal Donor-Chiral Bridge-Acceptor (D-ChiB-A) complexes for selective transfer of light generated spins using chiral induced spin selectivity (CISS) effects. Quantum confined semiconductor nanocrystals (NCs), including 0D quantum dots (QDs), 1D nanorods (NRs), and 2D nanoplatelets (NPLs), are novel classes of materials with many potential applications of broad technical and societal impacts, including light emitting diodes, displays, spintronics and quantum information. The proposed research program is aimed at developing NC donor-chiral bridge-acceptor platforms with long electron spin lifetime and high spin transfer selectivity for potential applications in quantum information processing. The proposed research, education and outreach activities offer opportunities for training and expanding the STEM workforce to meet the needs of the rapidly evolving and increasing technology heavy economy. The proposed research contains three interconnected specific aims. In Aim I, the team will develop methods to increase the spin lifetime by extending the electron-hole separation in three component NPL heterostructures. The NPL heterostructures with the longest spin lifetime will be used to construct D-ChiB-A complexes. In Aim II, the team will investigate CISS effects in photoinduced electron transfer in these D-ChiB-A complexes in two platforms that can achieve net spin orientation relative to electron transfer direction. In Aim III, the team will design and fabricate mix-layered 2D chiral perovskites to observe CISS effects in photo-induced ET from thinner 2D layers to thicker 2D layers (or 3D perovskites). The proposed direct time-resolved measurements of novel platforms allow systematic examination of key factors that influence CISS effects in photoinduced electron transfer, providing new mechanistic insights to advance current theoretical models. 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.