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Recently, significant progress has been made in colloidal quantum dot (QD) based optoelectronic devices for solar energy conversion, such as solar cells, luminescent solar concentrators, and solar-driven photoelectrochemical devices. In this Research Update, we summarized the most recent works on the QD based optoelectronic devices. Particularly, we focused on the effect of the QD structure on the functional properties of QD based devices. The major factors that determine the efficiency of the optoelectronic devices were discussed. In the end, we proposed potential ways to address the future challenges and opportunities of this field. [ABSTRACT FROM AUTHOR]

Colloidal Carbon dots (C-dots) have been used as promising emitters for luminescent solar concentrators (LSCs) due to its high quantum yield, low-cost, non-toxic and simple synthetic method. While it is still very challenging to fabricate high-efficiency LSCs based on C-dots because of strong spectral overlap between the absorption and emission. It is still unclear how the refractive index of the C-dots layer affects the optical properties of LSCs. Here we used liquid junction LSCs as an example to investigate the refractive index effect. A large-area (∼100 cm2) LSC was fabricated by injecting C-dots/polyvinylpyrrolidone solution into a glass mold. The refractive index of the polymer solution can be well controlled in the range of 1.33–1.44 by simply enhancing the polymer concentration. The reabsorption energy loss and the optical efficiency of the LSCs are strongly dependent on the refractive index of the polymer solution. The LSC based on C-dots/polymer exhibits refractive index dependent optical efficiency, as high as ∼0.92% under sunlight illumination, which is 27% enhancement in efficiency over the LSC based on C-dots dispersed in methanol. [ABSTRACT FROM AUTHOR]

Luminescent solar concentrators (LSCs) can serve as large-area sunlight collectors, are suitable for applications in high-efficiency and cost-effective photovoltaics (PVs), and provide adaptability to the needs of architects for building-integrated PVs, which makes them an attractive option for transforming buildings into transparent or non-transparent electricity generators. Compared with traditional organic dyes, colloidal semiconducting quantum dots (QDs) are excellent candidates as emitters for LSCs because they exhibit wide size/shape/composition-tunable absorption spectra ranging from ultraviolet to near infrared, significantly overlapping with the solar spectrum. They also feature narrow emission spectra, high photoluminescence quantum yields, high absorption coefficients, solution processability and good photostability. Most importantly, QDs can be engineered to provide a minimal overlap between absorption and emission spectra, which is key to the realization of large-area LSCs with largely suppressed reabsorption energy losses. In this review article, we will first present and discuss the working principle of LSCs, the synthesis of colloidal QDs using wet-chemistry approaches, the optical properties of QDs, their band alignment and the intrinsic relationship between the band energy structure and optical properties of QDs. We focus on emerging architectures, such as core/shell QDs. We then highlight recent progress in QD-based LSCs and their anticipated applications. We conclude this review article with the major challenges and perspectives of LSCs in future commercial technologies. [ABSTRACT FROM AUTHOR]

The fabrication of a low reabsorption emission loss, high efficient luminescent solar concentrator (LSC) is demonstrated by embedding near infrared (NIR) core/shell quantum dots (QDs) in a polymer matrix. An engineered Stokes shift in NIR core/shell PbS/CdS QDs is achieved via a cation exchange approach by varying the core size and shell thickness through the refined reaction parameters such as reaction time, temperature, precursor molar ratio, etc. The as-synthesized core/shell QDs with high quantum yield (QY) and excellent chemical/photostability exhibit a large Stokes shift with respect to the bare PbS QDs due to the strong core-to-shell electrons leakage. The large-area planar LSC based on core/shell QDs exhibits the highest value (6.1% with a geometric factor of 10) for optical efficiency compared to the bare NIR QD-based LSCs and other reported NIR QD-based LSCs. The suppression of emission loss and the broad absorption of PbS/CdS QDs offer a promising pathway to integrate LSCs and photovoltaic devices with good spectral matching, indicating that the proposed core/shell QDs are strong candidates for fabricating high efficiency semi-transparent large-area LSCs. [ABSTRACT FROM AUTHOR]

Luminescent solar concentrators (LSCs) are able to efficiently harvest solar energy through large‐area photovoltaic windows, where fluorophores are delicately embedded. Among various types of fluorophores, all‐inorganic perovskite nanocrystals (NCs) are emerging candidates as absorbers/emitters in LSCs due to their size/composition/dimensionality tunable optical properties and high photoluminescence quantum yield (PL QY). However, due to the large overlap between absorption and emission spectra, it is still challenging to fabricate high‐efficiency LSCs. Intriguingly, zero‐dimensional (0D) perovskites provide a number of features that meet the requirements for a potential LSC absorber, including i) small absorption/emission spectral overlap (Stokes shift up to 1.5 eV); ii) high PL QY (>95% for bulk crystal); iii) robust stability as a result of its large exciton binding energy; and iv) ease of synthesis. In this work, as a proof‐of‐concept experiment, Cs4PbBr6 perovskite NCs are used to fabricate semi‐transparent large‐area LSCs. Cs4PbBr6 perovskite film exhibits green emission with a high PL QY of ≈58% and a small absorption/emission spectral overlap. The optimized LSCs exhibit an external optical efficiency of as high as 2.4% and a power conversion efficiency of 1.8% (100 cm2). These results indicate that 0D perovskite NCs are excellent candidates for high‐efficiency LSCs compared to 3D perovskite NCs. [ABSTRACT FROM AUTHOR]

The fabrication of a low reabsorption emission loss, highly efficient luminescent solar concentrator (LSC), based on near infrared core/shell quantum dots embedded in a polymer matrix is demonstrated in article number 1501913, by Haiguang Zhao, Alberto Vomiero, Federico Rosei, and co‐workers. The semi‐transparent LSC exhibits an optical efficiency of 6.1% for a geometric factor G equal to 10, which is unprecedented for planar LSCs based on near infrared quantum dots. [ABSTRACT FROM AUTHOR]

• A triple-layer LSC was fabricated, with an external optical efficiency of 9.1 %, and a PCE of 6.0 %. • The blue-, green- and orange- emitting C-dots have a quantum yield of 90 %, 73 %, and 72 %. • The multilayer LSCs have high CRI above 80 and AVT above 70 %, suitable for efficient BIPVs. Compared to the silicon-based photovoltaics, large-area luminescent solar concentrators (LSCs) can be used as smart PV window for building-integrated photovoltaics (BIPVs). However, because of the low quantum yield of the fluorophores, and reabsorption energy loss, the current obtained large-area LSCs have low optical efficiency. Herein, we demonstrated highly efficient and semitransparent multilayer LSCs based on three types of carbon quantum dots (C-dots). The blue and green C-dots were synthesized using vacuum heating approach and the orange C-dots were synthesized using solvothermal approach. The as-prepared B-, G- and O-C-dots have the QYs of 90 %, 73 % and 72 %, respectively, with large Stokes shift (0.37–0.73 eV). By optimizing the concentration of the C-dots in each layer, the best LSC (100 cm2) with multilayer structure exhibited an external optical efficiency of 9.1 %, and a power conversion efficiency (PCE) of 6.0 %, which are higher than that of most of reported LSCs. The simulations indicate that optimized multilayer LSCs could have a theoretical external optical efficiency over 12 % for 1 m2 devices. Besides high optical efficiency, the multilayer LSCs also have high Color Rendering Index (above 80) and high average visible transmission (above 70 %), which make the as-prepared LSCs suitable for potential commercial BIPVs. [ABSTRACT FROM AUTHOR]

• Eco-friendly CuGaAlS/ZnS core/shell QDs were successfully synthesized. • Optical properties of QDs can be tuned by varying the copper contents. • The optimized QDs show a high PLQY of 91% with a large Stokes-shift. • High-performance and large-area QDs-based LSC device is fabricated. Luminescent solar concentrators (LSCs) fabricated using colloidal quantum dots (QDs) are considered as promising cost-effective solar collectors for future building-integrated photovoltaics (BIPV). Nevertheless, the solar-to-electricity conversion efficiency of the LSCs is commonly low due to limited quantum efficiency and large reabsorption loss of QDs. In addition, most of the efficient LSCs contain heavy metal-based QDs, limiting their potential commercial applications. Herein, we demonstrate a novel type of eco-friendly CuGaAlS/ZnS (CGAS/ZnS) core/shell QDs with efficient surface passivation and manipulated their optical properties by varying the copper contents, which effectively regulates the intrinsic band structure and radiative recombination dynamics. As a result, the optimal Cu-deficient CGAS/ZnS core/shell QDs exhibit the highest photoluminescence quantum yield (PLQY) of ∼ 91 % and large Stokes shift (∼0.81 eV). The prepared QDs were applied as emitters and integrated in polymer matrix to fabricate LSCs (10 × 10 × 0.15 cm3), delivering an unprecedented power conversion efficiency (PCE) of 4.29 % under standard one sun AM 1.5G illumination (100 mW cm−2). Our results imply that tuning the components of multinary environment-friendly core/shell QDs endows the feasibility to realize low-cost and high-efficiency BIPV applications. [ABSTRACT FROM AUTHOR]