Photogenerating polarized spin states in quantum dot – molecule conjugates
Jacob Olshansky a, Autumn Lee a, Frida Hernandez a, Amisha Jain a, Jens Niklas b, Oleg Poluektov b, Mandefro Teferi b, Ming Lee Tang c, Kefu Wang c, Tiffany Tran c, Tomoyasu Mani d
a Amherst College, East Drive, 25, Amherst, United States
b Argonne National Lab
c University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, 84112, United States
d University of Connecticut, Civil & Environ. Engr., 261 Glenbrook Rd U-3037, Storrs, CT, 06269
Poster, Jacob Olshansky, 031
Publication date: 15th May 2025

Organic molecules and quantum dots (QDs) have both shown promise as materials that can host quantum bits (qubits). This is in part because of their synthetic tunability. The current work employs a combination of both materials to demonstrate a series of tunable quantum dot – organic molecule conjugates that can both host photogenerated spin-based qubit pairs (SQPs) and sensitize molecular triplet states. The photogenerated qubit pairs, composed of a spin-correlated radical pair, are particularly intriguing since they can be initialized in well-defined, non-thermally populated, quantum states. Additionally, the radical pair enables charge recombination to a polarized molecular triplet state, also in a well-defined quantum state. The materials underlying this system are an organic molecular chromophore and electron donor, 9,10-bis(phenylethynyl)anthracene, and a quantum dot acceptor composed of ZnO. We prepare a series of quantum dot – molecule conjugates that possess variable quantum dot size and two different linker lengths connecting the two moieties. Optical spectroscopy revealed that the QD – molecule conjugates undergo photoexcited charge separation to generate long-lived charge-separated radical pairs. The resulting spin states are probed using light-induced time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy, revealing the presence of singlet-generated spin-correlated radical pairs (SCRPs), and molecular triplet states. Notably, the EPR spectra of the radical pairs are dependent on the geometry of this highly tunable system. The g value of the ZnO QD anion is size tunable, and the linewidths are influenced by radical pair separation. Overall, this work demonstrates the power of synthetic tunability in adjusting the spin specific addressability, satisfying a key requirement of functional qubit systems. 

© FUNDACIO DE LA COMUNITAT VALENCIANA SCITO
We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info