• membranes;
  • photonic crystals;
  • self assembly;
  • silicon solar cells;
  • thin films
Thumbnail image of graphical abstract

To enhance light trapping, M. Qi, P. Bermel, and co-workers use 3D photonic crystals (PhCs) as back-reflectors for solar cells. On page 692, a novel S5 process is developed to form a freestanding, self-assembled, inverse opal PhC, which is then transferred onto a commercial thinfilm silicon solar cell. As illustrated in the image, light impinging onto the PhC not only reflects but also diffracts back into the solar cell, resulting in increased electron–hole pair generation and a material efficiency enhancement of 10%.