Enhanced performance of solar cells with anti-reflection layer fabricated by nano-imprint lithography

Because of increase in demand for clean energy sources, photovoltaic device is becoming more important as a new power plant. To replace fossil fuels with photovoltaics, generating electricity with solar cells should meet cost effectiveness and high efficiency. An anti-reflection technique is one of the effective methods to achieve high efficiency.To reduce the reflection at the surface of concentrated photovoltaic device, a nanometer scale dot-pattern array was formed on the surface of GaInP/Ga(In)As/Ge solar cells by nano-imprint lithography. Since this nano-pattern is smaller than the wavelength of visible light, the effective refractive index near the surface changes gradually. Thus, the reflection of the light at the surface with moth-eye structure can be effectively reduced for overall spectral region. As a result, a solar cell with the moth-eye pattern as an anti-reflection layer showed lower reflectance and enhanced total conversion efficiency, compared to a solar cell without a moth-eye patterned layer.The patterned solar cell was characterized using UV–vis spectrophotometer, atomic force microscope (AFM) and scanning electron microscope (SEM), and its total conversion efficiency was measured by solar simulator.