For increasing the efficiency of a solar cell varies techniques are possible. For example using micrometer sized structures the light path though the solar cell can be increased by scattering on the back-side or antireflection structures on the front-side are possible. Making use of direct laser writing (DLW), where a three-dimensional architecture can be created in a photoresist on a hundreds of nanometers scale we are able to implement an inexhaustible number of designs.
While fabrication has been shown an investigation of novel and optimized designs has not been done. Your work would involve a literature review for structures, coming up with your own patterns, and performing simulations using ray tracing software. The project can possibly be extended to programming the designed structures and their fabrication.
Further information on the Institute of Microstructure Technology (IMT): http://www.imt.kit.edu/english/index.php