Anomalous Stokes shift of colloidal quantum dots and their influence on solar cell performance
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We report an anomalous Stokes shift effect observed in colloidal solutions containing down-shifting Carbon quantum dots (CQDs) of different sizes that is expected to have a positive influence on the power conversion efficiency of photovoltaic structures. Specifically, with an excitation wavelength of 390 nm, individual colloidal solutions of CQDs whose diameter was determined by the applied current during synthesis, exhibited photoluminescent (PL) emission wavelength peaks centered at 420 nm. However, the colloidal solution comprising the mixture of all the previously synthesized CQDs of different diameters was observed to have an anomalous PL Stokes shift centered at 515 nm. Furthermore, the aforementioned anomalous SSE was also observed in CdTe QDs when added to the CQD mixed-solution (CMS). Thus, whereas a mixture of CdTe QDs of different sizes, exhibited a down-shifted photoluminescence centered at 555 nm, the peak was observed to have an anomalous Stokes shift centered at 580 nm when combined with the CMS. Quantum dot characterization included crystal structure analysis as well as photon absorption and photoluminescence wavelengths. Subsequently, the synthesized QDs were dispersed in a polymeric layer of PMMA and incorporated on functional and previously characterized solar cells, to quantify their influence in the electrical performance of the photovoltaic devices. The observations indicate an improvement in the PCE of 4.6% when incorporating Carbon QDs, 2.9% with CdTe QDs and 4.8% when employing both C and CdTe QDs.
We thank the US Army Research Office, for the financial support provided for this project (Grant W911NF-13-1-0110), National Science Foundation Grant No. ECCS 1650571 and CONACYT for a student fellowship.
- Ayón A, Tronco-Jurado U, Lopez-Delgado R, Sharma M, Saucedo-Flores E, Alvarez-Ramos E (2015) Influence of Au/Ag nanostars and CdTe quantum dots on photon manipulation. In: Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2015 Transducers-2015 18th International Conference on. IEEE, pp 1436–1439Google Scholar
- Fuyuno N, Kozawa D, Miyauchi Y, Mouri S, Kitaura R, Shinohara H, Matsuda K et al. (2013). Size-dependent luminescence properties of chromatographically-separated graphene quantum dots. arXiv preprint. arXiv:1311.1684
- Kurtin J (2011) Improved solar cell efficiency through the use of an additive nanostructure-based optical downshifter. Contract 303:275–3000Google Scholar
- Pelayo E, Zazueta A, López-Delgado R, Saucedo E, Ruelas R, Ayón A (2016) Red-shift of the photoluminescent emission peaks of CdTe quantum dots due to the synergistic interaction with carbon quantum dot mixtures. In: Journal of Physics: Conference Series, vol 773, no. 1. IOP Publishing, pp 012053Google Scholar
- Saucedo-Flores E, Ruelas R, Rangel V, Tronco U, Ayón A (2014) Modelado del confinamiento y la luminiscencia en nanopartículas de seleniuro y telururo de cadmio. Rev Iberoam Cien 1(7):113–120Google Scholar
- Taki M (2013) Structural and optical properties of cadmium telluride CdXTe1-Xthin film by evaporate. Int J Appl Innov Eng Manage 2(5):413–417Google Scholar