The efficiency of silicon solar cells is limited to 29%. One possible way of breaking this limit uses a process called singlet fission, converting a high energy photon into two lower energy photons. An electron-hole pair is created in an organic semiconductor; this then splits into two lower energy electron-hole pairs. If these can be transferred to an inorganic semiconductor nanocrystal, they can recombine to emit lower energy photons. The efficiency of this process depends critically on the nature of the interface between the nanoparticle and the organic material. The nanoparticles have short organic groups - ligands –attached to their surfaces. Our experiment will determine how many of these ligands there are, how they are arranged, and how easily they can replaced by other groups. The resulting insights will help us to design processing routes to put this idea into practise.