Increased omnidirectional light absorbance by using hollow silica nanoparticles in an anti-reflective pattern for efficient organic photovoltaic devices

We investigated a single-layer low refractive index anti-reflection (AR) coating on an organic photovoltaic device, using hollow silica nanoparticles, as shown in a cross-sectional TEM image. The PCE (6.53%) of the device with the AR pattern layer was improved, which contributed to the increased light absorption in the broadband range and charge generation at normal incidence observed by optical and electrical analysis, respectively. Comparing the photovoltaic performance of the devices without and with the AR pattern layer by hollow silica nanoparticles, the AR pattern achieved an angle of incidence (AOI) improvement of averaged absorbance reduction of 45% and 74% for AOIs of 30 and 60 degrees, compared to that of the bare substrate. Consequently, the AR pattern layer showed excellent broadband and omnidirectional AR properties, and improved the performance of the device at various AOIs. The AR pattern layer from silica nanoparticles can be a useful approach for reducing reflectance in solar devices by a simple coating process, which will contribute to higher performance of organic photovoltaic devices.