3D-printed external light traps for solar cells

We demonstrate a universally applicable 3D-printed external light trap for solar cells. We placed a macroscopic external light trap made of smoothened, silver coated plastic at the sun-facing surface of different types of solar cells. The trap consists of a reflective parabolic concentrator on top of a reflective cage. The trap directs the light that is reflected upwards by the solar cell back towards the solar cell. Due to this retro-reflection the light traverses the solar cell several times resulting in a broadband absorption enhancement. We present a 15–27% efficiency enhancement for crystalline silicon, thin film nanocrystalline silicon and organic solar cells.