This book introduces the light management in amorphous silicon thin film solar cells through nanoparticles and nanostructures. The near-field light concentration from small metallic nanoparticles is utilised to significantly improve the solar cell conversion efficiency. For the first time, a novel nanoparticle imprinting technique is developed for the ultra-thin a-Si solar cell, leading to a 50% absorption enhancement in the solar cells. Through the combination of the imprinting technique and the designed lumpy nanoparticle structure for solar cells, a 20 nm thick a-Si solar cell can achieve a comparative absorption to a 300 nm thick standard a-Si solar cell.