Absorption Enhancement in “Giant” Core/Alloyed-Shell Quantum Dots for Luminescent Solar Concentrator

Abstract

Luminescent solar concentrators (LSCs) can potentially reduce the cost of solar cells by decreasing the photoactive area of the device and boosting the photoconversion efficiency (PCE). This study demonstrates the application of "giant" CdSe/Cd Pb S core/shell quantum dots (QDs) as light harvesters in high performance LSCs with over 1.15% PCE. Pb addition is critical to maximize PCE. First, this study synthesizes "giant" CdSe/Cd Pb S QDs with high quantum yield (40%), narrow size distribution (<10%), and stable photoluminescence in a wide temperature range (100-300 K). Subsequently these thick alloyed-shell QDs are embedded in a polymer matrix, resulting in a highly transparent composite with absorption spectrum covering the range 300-600 nm, and are applied as active material for prototype LSCs. The latter exhibits a 15% enhancement in efficiency with respect to 1% PCE of the pure-CdS-shelled QDs. This study attributes this increase to the contribution of Pb doping. The results demonstrate a straightforward approach to enhance light absorption in "giant" QDs by metal doping, indicating a promising route to broaden the absorption spectrum and increase the efficiency of LSCs.

Limits of Visibly Transparent Luminescent Solar Concentrators

“…One promising approach is the use of core/shell structured nanocrystals, forming quasi-type II heterojunction where the shell has larger energy bandgap and acts as a light absorbing antenna that transfers the energy to the core crystal as the light emitter. [11,51,[73][74][75] Impurity-doping and alloying are both alternative approaches to tackle the reabsorption problem. For example, in Mn-doped ZnSe/ZnS core/shell NCs, small amount (0.1-1%) of Mn 2+ introduces new localized excited energy states within the bandgap of ZnSe resulting in exhibit enhanced downshifted luminescence.…”

Resonant Energy Transfer can Trigger Multiexciton Recombination in Dense Quantum Dot Ensembles

“…Colloidal semiconductor nanocrystals (NCs) [quantum dots (QDs)], attract widespread attention due to their potential use as a tunable optoelectronic material . They are efficient light emitters and absorbers and well‐suited for applications such as lasing, photodetection, and solar energy conversion . Among the available structures, core/shell QDs, where the shell passivates the core surface atoms, are highly developed .…”

“…[1] They are efficient light emitters and absorbers and well-suited for applications such as lasing, photodetection, and solar energy conversion. [2][3][4][5][6][7][8] Among the available structures, core/shell QDs, where the shell passivates the core surface atoms, are highly developed. [9,10] The resulting reduced overlap with trap states at the surface improves the optical properties of the QDs.…”

Long‐Lasting Nanophosphors Applied to UV‐Resistant and Energy Storage Perovskite Solar Cells

“…Some photoluminescent materials are able to convert UV photons into lowenergy photons, which can prevent UV light from negatively interacting with perovskite photoactive materials. [13][14][15] Specifically, a multifunctional lightshifting V570 coating on dye-sensitized solar cell not only resulted in a 60% PCE improvement, but also prevented dye decomposition. [12] Therefore, luminescence downconverting materials can not only reduce the corrosion effect of UV on devices but may also improve the PCE of the devices.…”

“…The introduction of UV-blocking and UV-conversion materials has represented two very important issues to be addressed in the organic, quantum dots, and dyesensitized solar cell. [13][14][15] Specifically, a multifunctional lightshifting V570 coating on dye-sensitized solar cell not only resulted in a 60% PCE improvement, but also prevented dye decomposition. [13] Trans-5-(p-(N,N-diphenylamino)styril)-1,3di(2-pyridyl)-benzene as a luminescent downshifting layer was also coated on organic solar cells to achieve ≈4% PCE improvement and long-term stability.…”