Highly efficient large-area colourless luminescent solar concentrators using heavy-metal-free colloidal quantum dots

Abstract

Luminescent solar concentrators serving as semitransparent photovoltaic windows could become an important element in net zero energy consumption buildings of the future. Colloidal quantum dots are promising materials for luminescent solar concentrators as they can be engineered to provide the large Stokes shift necessary for suppressing reabsorption losses in large-area devices. Existing Stokes-shift-engineered quantum dots allow for only partial coverage of the solar spectrum, which limits their light-harvesting ability and leads to colouring of the luminescent solar concentrators, complicating their use in architecture. Here, we use quantum dots of ternary I-III-VI2 semiconductors to realize the first large-area quantum dot-luminescent solar concentrators free of toxic elements, with reduced reabsorption and extended coverage of the solar spectrum. By incorporating CuInSexS2-x quantum dots into photo-polymerized poly(lauryl methacrylate), we obtain freestanding, colourless slabs that introduce no distortion to perceived colours and are thus well suited for the realization of photovoltaic windows. Thanks to the suppressed reabsorption and high emission efficiencies of the quantum dots, we achieve an optical power efficiency of 3.2%. Ultrafast spectroscopy studies suggest that the Stokes-shifted emission involves a conduction-band electron and a hole residing in an intragap state associated with a native defect.

Reabsorption Losses in Luminescent Solar Concentrators: Effect of the Band Gap of Semiconductor Quantum Dots, their Size and Dispersion

“…The crossing point position is always below 1 and we can use this value in percent as a measure of the reabsorption. As it is shown in [6], the losses due to the reabsorption process can significantly reduce the LSC efficiency. To mitigate these losses, it is necessary to increase a separation (h) of the absorption and emission processes in energy.…”

Sol-Gel Glasses Doped with Pt-Acetylides and Gold Nanoparticles for Enhanced Optical Power Limiting

“…Colour filters have the draw-back of degrading the image [22,23]. A colour-degraded image induce varying degrees of "induced colour blindness" [24]. The larger wavelength span protected, the larger amount of information never reach the image sensor.…”

Excited-State Dynamics in Colloidal Semiconductor Nanocrystals

“…In type-I 1/2 (or quasi-type-II) hetero-NCs one carrier is delocalized over the whole volume of the hetero-NC, while the other is localized in one of the segments (e.g., CdSe/CdS, ZnSe/CdSe). This allows the electron-hole spatial overlap to be tailored by controlling the size, shape, and composition of each segment of the hetero-NC, which has a dramatic impact on several properties (viz., quantum yields, stability, PL wavelength [15,16,21,60,61], reabsorption cross section [22,29,[62][63][64], radiative lifetimes [60,[64][65][66], exciton-phonon coupling strength [67][68][69], Auger recombination [66,[70][71][72], hot carrier relaxation [51,73], thermal quenching [74,75]). The general trend is that the exciton lifetime, exciton-phonon coupling, and PL wavelength increase when going from the type-I to the type-II localization regimes, while Auger recombination rates and hot carrier relaxation rates are reduced.…”

“…Since the pioneering work of Brus, Ekimov, and many others in the early 1980-1990s [1][2][3][4][5][6][7][8][9][10][11][12][13], the study of semiconductor nanocrystals (NCs) has developed into a mature, dynamic and multidisciplinary research field, which attracts increasing attention worldwide, both for its fundamental challenges and its potential for a number of technologies (light emitting devices, solar cells, luminescent solar concentrators, optoelectronics, sensing, thermoelectrics, biomedical applications, catalysis) [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Colloidal semiconductor NCs are particularly attractive, since they consist of an inorganic core that is coated with a stabilizing layer of (usually) organic ligand molecules.…”