After few decades of investigations just a handful of materials undergoing singlet fission are known despite the strong interest for fundamental science (photophysics, quantum dynamics, quantum chemistry) and the acknowledged potential for technological applications in photovoltaics and other optoelectronics devices. The limited number of available materials is very concerning because one needs a large pool of compounds to optimize device performance, processing and integration with other materials. Moreover, the fundamental understanding is severely limited when the systems that can be studied are so few. This proposal will address the key limitation of the field, identifying a set of materials suitable for singlet fission by an innovative high-throughput computational screening approach. For all the new candidates found within this project a synthetic route is available and the crystal structure is known, i.e. the prediction will be about EXISTING MOLECULAR MATERIALS rather than hypothetical molecules. Unsuitable molecular arrangements in the crystal are taken into account and all the criteria for singlet fission can be imposed in parallel. The prediction will be accompanied by a level of confidence obtained by calibrating the method against a large number of know experimental data (Objective 1). Our preliminary work on a small sample of the compounds to be screened and on the calibration of the methodology has already led to the discovery of few highly promising candidates. Our projections indicate that more than a hundred new molecules (not already known to undergo singlet fission) can be discovered in this way. The computational screening is followed by a thorough post-processing analysis to identify new design rules for singlet fission and assess the validity of the old ones. These rules will guide the development of new singlet fission materials from the lead compounds identified by this work (Objective 2). The preliminary experimental validation of the prediction is part of this project (Objective 3). A small sub-set of molecules to be characterized optically will be selected among those easier to obtain from collaborators or commercially. The optical characterization will be performed by our partner Prof. S. Reineke (TU, Dresden).