The Solar Photochemistry core program at NREL, funded by the Office of Basic Energy Science, focuses on fundamental research of solar photoconversion in molecular, nanoscale, and semiconductor systems to capture, control, and convert solar radiation with high efficiency into electrochemical potential for electricity, chemicals, or fuels.
Projects are defined under three thrust areas:
Excitons to Charge Carriers in Molecular and Nanoscale Systems: We seek to understand the fundamental processes and dynamics of excitons in molecular and nanoscale systems to direct charge and energy flow in efficient solar generation, separation, collection, and utilization.
Quantum-Confined Semiconductors: We aim to control photophysical and electronic behavior in isolated and ensemble nanostructures by using size, shape, composition, coupling, and surface chemistry. Further advances in performance and stability of nanostructure-based devices are required to achieve higher efficiency and/or reduced cost compared with bulk counterparts.
Currently, we are investigating nanoscale phenomena related to the following: 1) Slowed hot-carrier cooling, 2) Efficient multiple exciton generation (MEG), 3) Enhanced light absorption, and 4) Long-lived charge-separated states.
Solar Fuels: We probe energy transfer, charge transport, and reactivity in subsystems with a semiconductor/electrolyte interface.
Understanding such novel behavior requires exquisite synthetic control and sophisticated experiments. Thus, we are continuously updating our capabilities to complement our long-standing expertise. Our primary techniques include the following:
Visible and infrared temperature-dependent steady-state photoluminescence (PL), including an integrating sphere for determining quantum yield of solutions and films
Picosecond to microsecond time-resolved photoluminescence (TRPL) via time-correlated single-photon counting and streak cameras with detection from ultraviolet through near-infrared
Femtosecond through microsecond transient absorption spectroscopy (TAS), from ultraviolet through mid-infrared
Time-resolved terahertz (THz) spectroscopy for free charge-carrier dynamics
Time-resolved microwave conductivity (TRMC) for long-lived carrier-production yields
Ultraviolet-visible (UV-VIS), nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy for surface-ligand chemistry and doping
Transient grating spectroscopy for exciton diffusion and spin-relaxation dynamics
X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) for band-level positions
Non-thermal plasma deposition of nanoparticles
Microwave and high-performance liquid chromatography (HPLC) techniques for heterostructure synthesis and separation
Photothermal deflection spectroscopy for bandtail widths
Major Recent Publications
Park, J.; Reid, O. G.; Blackburn, J. L.; Rumbles, G. Photoinduced Spontaneous Free-Carrier Generation in Semiconducting Single-Walled Carbon Nanotubes. Nat Comms 2015, 6, 8809. DOI: 10.1038/ncomms9809
Wan, Y.; Guo, Z.; Zhu, T.; Yan, S.; Johnson, J.; Huang, L. Cooperative Singlet and Triplet Exciton Transport in Tetracene Crystals Visualized by Ultrafast Microscopy. Nature Chemistry 2015, 7 (10), 785–792. DOI: 10.1038/nchem.2348
Ihly, R.; Mistry, K. S.; Ferguson, A. J.; Clikeman, T. T.; Larson, B. W.; Reid, O.; Boltalina, O. V.; Strauss, S. H.; Rumbles, G.; Blackburn, J. L. Tuning the Driving Force for Exciton Dissociation in Single-Walled Carbon Nanotube Heterojunctions. Nature Chemistry 2016, 8 (6), 603–609. DOI: 10.1038/nchem.2496
Miller, E. M.; Kroupa, D. M.; Zhang, J.; Schulz, P.; Marshall, A. R.; Kahn, A.; Lany, S.; Luther, J. M.; Beard, M. C.; Perkins, C. L.; van de Lagemaat, J. Revisiting the Valence and Conduction Band Size Dependence of PbS Quantum Dot Thin Films. Acs Nano 2016, 10 (3), 3302–3311. DOI: 10.1021/acsnano.5b06833
Yang, Y.; Ostrowski, D. P.; France, R. M.; Zhu, K.; van de Lagemaat, J.; Luther, J. M.; Beard, M. C. Observation of a Hot-Phonon Bottleneck in Lead-Iodide Perovskites. Nat Photonics 2015, 10 (1), 53–59. DOI: 10.1038/nphoton.2015.213
Yang, Y.; Yan, Y.; Yang, M.; Choi, S.; Zhu, K.; Luther, J. M.; Beard, M. C. Low Surface Recombination Velocity in Solution-Grown CH3NH3PbBr3 Perovskite Single Crystal. Nat Comms 2015, 6, 7961. DOI: 10.1038/ncomms8961
Gu, J.; Yan, Y.; Young, J. L.; Steirer, K. X.; Neale, N. R.; Turner, J. A. Water Reduction by a p-GaInP2 Photoelectrode Stabilized by an Amorphous TiO2 Coating and a Molecular Cobalt Catalyst. Nat Mater 2015, 15 (4), 456–460. DOI: 10.1038/nmat4511
Yang, Y.; Gu, J.; Young, J. L.; Miller, E. M.; Turner, J. A.; Neale, N. R.; Beard, M. C. Semiconductor Interfacial Carrier Dynamics via Photoinduced Electric Fields. Science 2015, 350 (6264), 1061–1065. DOI: 10.1126/science.aad3459
The Chemistry and Nanoscience Center is part of the Materials and Chemical Science and Technology directorate, led by Associate Laboratory Director Bill Tumas.