The high hydrogen content of the a-Si:H shell is suggested to have a good-quality passivation effect [27]. In summary, the FTIR spectrum confirms the deposition of the a-Si:H over SiNWs with Bafilomycin A1 appropriate features. Figure 2 Transmittance spectra of planar SiNWs and thin a-Si:H shell. Figure 3 presents the reflection spectrum of a-Si:H/SiNWs and SiNWs. a-Si:H/SiNWs had suppressed the reflection to low values at incident light wavelength ranges from 250 to 1,000 nm. As

noted, the combination of a-Si:H shell over SiNW core reduces the average reflectance as low as 5.2%. Relying on previous studies, the low reflection of a-Si:H/SiNWs is mainly caused by the graded refractive index of the SiNW core [28]. GSK872 cost Moreover, the filling ratio between the SiNWs and substrate surface plays a vital role in reducing the reflection of the core/shell structures. While studying the a-Si:H thickness effect on the filling ratio, 30 nm was found to be the optimum thickness with respect to both the filling ratio and hence the light reflection [29]. Figure 3 Reflection spectrum of a-Si:H/SiNWs and SiNWs (a) and absorption spectrum from reflection and transmission results (b). Going back to earlier works, a-Si:H thin films reflect more than 45% of the incident light [30].

Thus, it is expected that the a-Si:H/SiNW structure will be a sufficient antireflection coating combining amorphous and crystalline silicon features. The absorption spectrum that was extracted from the measured reflection and Thymidylate synthase transmission results is shown in Figure 3. It is noticeable that a-Si:H/SiNWs show a superior absorption property with an average over 87% of the incident light. Note here that the recent simulated results predicted the absorption to be around 60% to 75% [29] for 1-μm thickness. Using SiNWs with 3-μm lengths in this work could be the cause of such increment. As well known, SiNWs reflect less light while increasing their thickness [18]. Another inspiring feature of the a-Si:H/SiNW absorption spectrum is the shifting of

the absorbed edge to near-infrared wavelengths. This shifting confirms the dual absorption function of both a-Si:H and SiNWs. Basically, each of them absorbed the wavelengths of the light which match to their energies. Comparing the absorption edges of our a-Si:H/SiNWs with those of amorphous silicon nanowires, it was found that the absorption edge located on the wavelength corresponds to the a-Si Selleck GDC-941 bandgap [31]. Lastly, broadband optical absorption combined with a low reflection value is a significant advantage of a-Si:H/SiNWs compared with a-Si thin films and silicon surfaces. This suggests that a-Si:H/SiNWs can be used as effective antireflection coating for silicon solar cells. Figure 4 and Table 1 present the electrical performance of a-Si:H/SiNW and SiNW solar cells.