Exciton recycling via InP quantum dot funnels for luminescent solar concentrators
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Exciton recycling via InP quantum dot funnels for luminescent solar concentrators Houman Bahmani Jalali1,§, Sadra Sadeghi2,§, Isinsu Baylam3,4, Mertcan Han5, Cleva W. Ow-Yang6, Alphan Sennaroglu3,4, and Sedat Nizamoglu1,2,5 () 1
Graduate School of Biomedical Sciences and Engineering, Koç University, Istanbul 34450, Turkey Graduate School of Material Science and Engineering, Koç University, Istanbul 34450, Turkey 3 Koç University Surface Science and Technology Center (KUYTAM), Koç University, Istanbul 34450, Turkey 4 Laser Research Laboratory, Koç University, Istanbul 34450, Turkey 5 Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey 6 Department of Material Science and Nano Engineering, Sabanci University, Istanbul 34956, Turkey § Houman Bahmani Jalali and Sadra Sadeghi contributed equally to this work. 2
© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 6 August 2020 / Revised: 20 October 2020 / Accepted: 22 October 2020
ABSTRACT Luminescent solar concentrators (LSC) absorb large-area solar radiation and guide down-converted emission to solar cells for electricity production. Quantum dots (QDs) have been widely engineered at device and quantum dot levels for LSCs. Here, we demonstrate cascaded energy transfer and exciton recycling at nanoassembly level for LSCs. The graded structure composed of different sized toxic-heavy-metal-free InP/ZnS core/shell QDs incorporated on copper doped InP QDs, facilitating exciton routing toward narrow band gap QDs at a high nonradiative energy transfer efficiency of 66%. At the final stage of non-radiative energy transfer, the photogenerated holes make ultrafast electronic transitions to copper-induced mid-gap states for radiative recombination in the near-infrared. The exciton recycling facilitates a photoluminescence quantum yield increase of 34% and 61% in comparison with semi-graded and ungraded energy profiles, respectively. Thanks to the suppressed reabsorption and enhanced photoluminescence quantum yield, the graded LSC achieved an optical quantum efficiency of 22.2%. Hence, engineering at nanoassembly level combined with nonradiative energy transfer and exciton funneling offer promise for efficient solar energy harvesting.
KEYWORDS energy transfer, indium phosphide, quantum dot, light harvesting, luminescent solar concentrator, luminescent solar concentrators (LSC)
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Introduction
The energy delivered by the Sun to the Earth in one hour (4.6 × 1020 Joules) is close to the global annual energy consumption [1]. Efficient collection of solar photons and subsequent conversion to electricity can significantly decrease the demand for fuel-based energy and lead to a clean and sustainable energy solution that can have positive impact on environment, economy, and health. For that, luminescent solar concentrators (LSCs) integrated with photovoltaics (PV) hold significant potential [2–6]. LSCs can advantageously absorb large-area sunlight, and the downconverted light is propagated by t
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