Figure 5 Cross-sectional morphology of SiNW array incorporated by P3HT/PCBM. The J-V characteristics of hybrid solar cells with different diameters of AgNPs #Selleck GSK3326595 randurls[1|1|,|CHEM1|]# compared to those of hybrid solar cells without AgNPs are shown in Figure 6. The short-circuit current density (J sc), open-circuit voltage (V oc), fill factor (FF), and efficiency (η) of all the cells are listed in Table 1. From the results presented in Figure 6 and Table 1, it can be found that the device performance of AgNP-decorated hybrid solar cells is improved compared to that of the reference device, which could be attributed to the enhanced light absorption
of the polymer film. The short-circuit current increases from J sc = 10.5 mA/cm2 for the reference cell to 16.6 mA/cm2 for the best AgNP-decorated cell, with an enhancement up to 58%. The current gain gives a rise of the conversion efficiency from NVP-LDE225 mouse η = 2.47% to 3.23%, whereas the fill factor reduces from 0.501 to 0.429. Within the group of AgNP-decorated cells, the diameter of the AgNPs is an important factor in determining the cell efficiency. As shown in the curves, as the AgNPs become bigger, the J sc of the cell increases. This improvement of J sc can be mainly attributed to the enhancement of light scattering as the AgNP diameter increases. That is to say, increased light scattering will lead to some increased lateral reflection
of light among the SiNWs and absorption of light in the polymer. Higher absorption of light will introduce more photogenerated carriers and lead to improved current density [1, 15]. Figure 6 J – V characteristics of SiNW/organic hybrid solar cell. The red dot line, blue up-triangle line, and green down-triangle line represent the J-V characteristics of SiNW arrays decorated with AgNPs with diameters of 19, 23, and 26 nm, respectively. The black square line represents the J-V characteristics of bare SiNW array without AgNPs. Table 1 Device performances of SiNW/organic hybrid solar cells Device
J sc(mA/cm2) V oc(V) FF (%) η (%) R S(Ω cm2) Without AgNPs 10.5 0.469 50.1 2.47 30.3 19 nm 14.1 0.458 43.4 2.81 26.8 23 nm 15.4 0.456 44.1 3.11 20.7 26 nm 16.6 0.455 42.9 3.23 19.8 However, we note that the V oc of AgNP-decorated cells decreases lightly. It has been reported that the Endonuclease passivation provided by the polymer and the interface area between the polymer and SiNWs (or AgNPs) could influence the open-circuit voltage of the devices [1]. In other words, increased AgNP diameter will lead to some increased interface area and hence decreased V oc. It should be mentioned that the fill factor of all the hybrid cells are still very low. The series resistance comes from defects in the SiNW array, and poor electrode contact might be responsible for the low value. External quantum efficiency (EQE) measurements of the cells with and without AgNPs have been carried out for comparison, as shown in Figure 7.