Search materials by HOMO, LUMO and work function
Indeed, Prof. Alán Aspuru-Guzik has placed his "clean energy project" database on the web in a searchable form.

At the moment, it covers ~2.3 million compounds.


  Use of the data requires citation of the appropriate literature sources. The data in this database is released under the Creative Commons Attribution ShareAlike license and therefore any academic publications associated with the CEPDB should be appropriately cited.


As you point out, the database only covers HOMO and LUMO orbital eigenvalues. While this may not be the most useful for experimental applications (i.e., you really want ionization potentials and first excited state energies or electron affinities) it should be a helpful "first screen" to find interesting lead compounds.