The active layer of organic photovoltaic cells (OPVs) is typically a blend of p-and n-type semiconductors, and the arrangement of these materials largely affects the device performance. We have recently proposed a unique deposition technique in which α-diketone-type photoprecursors are solution-deposited and then subjected to in-situ photoreaction to form acene-based semiconductors, as an effective means for controlling the morphology and vertical composition profile in organic molecular blends. However, the applicability of this "photoprecursor approach" has been limited to p-type materials so far, restricting the flexibility in designing photovoltaic layers. Herein, we report α-diketone-type photoprecursors of two fullerene-anthracene conjugates which have been designed to serve as n-type material in OPVs. The new α-diketones, named N601DK and N602DK, are successfully applied to the photoprecursor approach, affording smooth thin films of the corresponding photoreaction products N601 and N602. The n-type materials thus produced are evaluated in bulk-heterojunction (BHJ) OPVs and found to show good photovoltaic response. Especially, N601 performs as well as PC 61 BM, a fullerene-based benchmark n-type material. These results will serve as a basis for further improvement of OPVs through optimization of the molecular arrangement in solution-processed photovoltaic layers. have been considered as the standard n-type materials in solutionprocessed organic photovoltaic layers. The strength of these compounds lies in the well-balanced electronic and electric properties of fullerene cages and the high processability derived from the flexible addend. Indeed, a large part of the OPV research reported so far, from the study of elementary processes and limiting factors to the optimization of material design and thin-film morphology, has been based on the use of PC 61 BM or PC 71 BM as n-type material. 3As such, although several high-performance nonfullerene n-type materials have been reported recently, 4-8 fullerenes are still attractive scaffolds in constructing new n-type molecules for OPVs, 9-11 if one considers their favorable characteristics and the rich accumulated knowledge.Meanwhile, we are applying a "photoprecursor approach" to the preparation of organic photovoltaic layers, in which semiconducting thin films are prepared by solution deposition of precursors followed by in-situ photoreaction to generate corresponding target compounds. Specifically, our process employs α-diketone-type photoprecursors that can be quantitatively converted to acene compounds with extrusion of carbon monoxide upon visible-light irradiation ( Figure 1a). 12 We have shown that this method is effective in preparing wellperforming photovoltaic layers comprising highly crystalline, scarcely soluble p-type molecular semiconductors which are otherwise hard to process by solution-based techniques. [13][14][15] The photoprecursor approach is also useful for the preparation of multilayer thin films by solution processes, provided that the solub...