Richard Spalding

Dr Richard Spalding BSc

Research Fellow
1st BSc Physics


My qualifications

Physics BSc 1st


Nicoletta Granchi, RICHARD JOHN SPALDING, Matteo Lodde, Maurangelo Petruzzella, Frank W. Otten, Andrea Fiore, Francesca Intonti, Riccardo Sapienza, MARIAN FLORESCU, Massimo Gurioli (2022)Near-Field Investigation of Luminescent Hyperuniform Disordered Materials, In: Advanced optical materials2102565 Wiley

Disordered photonic nanostructures have attracted tremendous interest in the past three decades, not only due to the fascinating and complex physics of light transport in random media, but also for peculiar functionalities in a wealth of interesting applications. Recently, the interest in dielectric disordered systems has received new inputs by exploiting the role of long-range correlation within scatterer configurations. Hyperuniform photonic materials, that share features of photonic crystals and random systems, constitute the archetype of systems where light transport can be tailored from diffusive transport to a regime dominated by light localization due to the presence of photonic band gap. Here, advantage is taken of the combination of the hyperuniform disordered (HuD) design in slab photonics, the use of embedded quantum dots for feeding the HuD resonances, and near-field hyperspectral imaging with sub-wavelength resolution in the optical range to explore the transition from localization to diffusive transport. It is shown, theoretically and experimentally, that photonic HuD systems support resonances ranging from strongly localized modes to extended modes. It is demonstrated that Anderson-like modes with high Q/V are created, with small footprint, intrinsically reproducible and resilient to fabrication-induced disorder, paving the way for a novel photonic platform for quantum applications.

Nasim Tavakoli, RICHARD JOHN SPALDING, Alexander Lambertz, Pepijn Koppejan, Georgios Gkantzounis, Chenglong Wan, Ruslan Röhrich, Evgenia Kontoleta, A. Femius Koenderink, Riccardo Sapienza, MARIAN FLORESCU, Esther Alarcon-Llado (2022)Over 65% Sunlight Absorption in a 1 μm Si Slab with Hyperuniform Texture, In: ACS photonics9(4)pp. 1206-1217 American Chemical Society

Thin, flexible, and invisible solar cells will be a ubiquitous technology in the near future. Ultrathin crystalline silicon (c-Si) cells capitalize on the success of bulk silicon cells while being lightweight and mechanically flexible, but suffer from poor absorption and efficiency. Here we present a new family of surface texturing, based on correlated disordered hyperuniform patterns, capable of efficiently coupling the incident spectrum into the silicon slab optical modes. We experimentally demonstrate 66.5% solar light absorption in free-standing 1 μm c-Si layers by hyperuniform nanostructuring for the spectral range of 400 to 1050 nm. The absorption equivalent photocurrent derived from our measurements is 26.3 mA/cm2, which is far above the highest found in literature for Si of similar thickness. Considering state-of-the-art Si PV technologies, we estimate that the enhanced light trapping can result in a cell efficiency above 15%. The light absorption can potentially be increased up to 33.8 mA/cm2 by incorporating a back-reflector and improved antireflection, for which we estimate a photovoltaic efficiency above 21% for 1 μm thick Si cells.