Graphene Quantum Dot Layers with Energy-Down-Shift Effect on Crystalline-Silicon Solar Cells

Abstract

Graphene quantum dot (GQD) layers were deposited as an energy-down-shift layer on crystalline-silicon solar cell surfaces by kinetic spraying of GQD suspensions. A supersonic air jet was used to accelerate the GQDs onto the surfaces. Here, we report the coating results on a silicon substrate and the GQDs' application as an energy-down-shift layer in crystalline-silicon solar cells, which enhanced the power conversion efficiency (PCE). GQD layers deposited at nozzle scan speeds of 40, 30, 20, and 10 mm/s were evaluated after they were used to fabricate crystalline-silicon solar cells; the results indicate that GQDs play an important role in increasing the optical absorptivity of the cells. The short-circuit current density was enhanced by about 2.94% (0.9 mA/cm(2)) at 30 mm/s. Compared to a reference device without a GQD energy-down-shift layer, the PCE of p-type silicon solar cells was improved by 2.7% (0.4 percentage points).

Enhanced Conversion Efficiency of III–V Triple-junction Solar Cells with Graphene Quantum Dots

“…After the depositon of GQDs, an enhancement of 2.94–6.1% and 2.7–14.9% has been observed in J SC and η of Si solar cells, respectively. The enhanced performance in Si solar cells was explained by the energy-down-shift effect due to GQDs12. In our opinion, the carrier injection from GQDs should also play a role in the enhanced conversion efficiency in the GQD-deposited Si solar cells since GQDs exhibit a lower work function (~3.7 eV) than that of Si (4.2 eV)13.…”

“…Other semiconductor solar cells could improve their conversion efficiency by using GQDs as well. Recently, performances of Si solar cells have been investigated by depositing GQDs on the surface of Si solar cells1112. After the depositon of GQDs, an enhancement of 2.94–6.1% and 2.7–14.9% has been observed in J SC and η of Si solar cells, respectively.…”

“…The photovoltaic performance made up by ZnO/GQD-based cells showed a value of high open circuit voltage (V OC ) of ~0.8 V and an internal quantum efficiency of 87%. Very recently, GQDs have been deposited as down-converters on silicon-related solar cells, improving the short circuit current (I sc ) and the conversion efficiency by 2.94–6.1% and 2.7–14.9%, respectively1112.…”

Colloidal N-Doped Graphene Quantum Dots with Tailored Luminescent Downshifting and Detection of UVA Radiation with Enhanced Responsivity

“…However, if E ph is larger than E g (as in the case of UV light), the photons are absorbed, but the excess energy ( E ph – E g ) is not used effectively for generation of photocurrent, and it causes electron thermalization. 35 As discussed earlier, the value of ESM characterizes the overlap between the emission band of LDS material and the EQE band of the used PC. In the present study, the value of ESM for the green luminescent N-GQD3 is found to be 4 times higher than that of direct UVA radiation (Table 1 and Figure 6b).…”

Correlated Roles of Temperature and Dimensionality for Multiple Exciton Generation and Electronic Structures in Quantum Dot Superlattices

“…29,30 Optical, electrical, thermal and mechanical properties of such QDSLs are thus determined not only by individual QDs, but also by the dimensionality dependent resonant couplings through the interior nano space among adjacent QDs tuned by ligand engineering down to subnanometer regime. 3,14,19,[31][32][33][34][35][36][37][38] Thus, the dimensionality in the QDSLs should be a crucial parameter for independent tailoring of the electronic and photoexcited properties including the multiple exciton generation (MEG) through which multiple electron-hole pairs can be produced; [39][40][41] the MEG is expected to increase solar cell efficiency by creating multiple carriers from a single photon absorption. 42 Meanwhile, temperature can be another important parameter to control the physical properties of the QDSLs.…”