Liu Y, Scully SR, McGehee MD, Liu J, Luscombe CK, Fréchet JM, Shaheen SE, Ginley DS. Dependence of band offset and open-circuit voltage on the interfacial interaction between TiO2 and carboxylated polythiophenes. J Phys Chem B. 2006 Feb 23;110(7):3257–61. doi: 10.1021/jp056576y. PMID: 16494337.