Low reflectivity in the UV to green light wavelength range gives promise Oligomycin A solubility dmso for multi-junction solar cells if more junctions are requested especially for high-band gap subcells. Figure 4 Reflectance values of bare T-J solar cell and T-J solar cells with Si 3 N
4 and ZnO nanotube coating, respectively. The photovoltaic I-V characteristics were measured under one sun AM1.5 (100 mW/cm2) solar simulator. The device parameters of Wnt inhibitor open-circuit voltage (V oc), short-circuit current (I sc), fill factor (FF) conversion efficiency (η), and quantum efficiency (QE) were measured. Figure 5a shows the I-V characteristics of T-J solar cells with and without a Si3N4 and ZnO nanotube structure. The efficiencies buy PFT�� of a T-J solar cell with and without a Si3N4 and ZnO nanotube structure are 19.3, 22.5, and 24.2%, respectively, as shown in Table 1. The short-circuit current density (J sc) increased from 12.5 to 13.2 and 13.2 to 13.9 mA/cm2 after the addition of a Si3N4 and ZnO nanotube on the solar cell, and the J sc was improved 5.3% in enhancement in overall
power conversion efficiency. The largest efficiency and J sc values were obtained for the T-J solar cell with ZnO nanotube. The reason for this is that a ZnO nanotube decreases the reflectance and increases the short-circuit current. The quantum efficiency of a solar cell is defined by the following equation: Figure 5 I-V characteristics of T-J solar cells and External quantum efficiency. (a) Photovoltaic I-V characteristics of T-J solar cell with and without Si3N4and ZnO nanotube structure, respectively. (b) External quantum efficiency of bare triple-junction (T-J) solar cell and T-J solar cell with DOK2 SiN4 and ZnO nanotube coating, respectively. Table 1 Measured illuminated electrical properties of bare triple (T-J) solar cell and T-J solar cell with SiN 4 and ZnO nanotube coating, respectively Sample V oc (V) J sc(mA/cm 2) FF (%) Efficiency (%) Bare T-J solar cell 2.2 12.5 71.2 19.3 With SiNx AR coating 2.3 13.2 74.5 22.5 With ZnO NW AR coating 2.3 13.9 74.8 24.2 (1) where
J sc (λ) is the total photogenerated short-circuit current density at a given wavelength λ, ϕ(λ) is the photon flux of the corresponding incident light, and q is the elementary charge [18]. We measured the spectral response of the external quantum efficiency (EQE), in which a xenon lamp and a halogens lamp were used as the illumination source sources. The EQE of the T-J solar cell device with SiN4 and ZnO nanotube coating, respectively, are presented in Figure 5b. Physically, EQE means the ability to generate electron-hole pairs caused by the incident photon [19]. The cell with ZnO nanotube coating shows an enhanced EQE in a range from of 350 to 1800 nm. The average EQE enhancements (△EQE) of the top and middle cells were 2.5 and 6.6%, respectively. This is due to the low reflection between the wavelength 350 to 500 nm, in respect to the solar cell coated with a ZnO nanotube.