Effect of a-Si:H–polymer interface on the behavior of hybrid solar cells

Organic photovoltaics (OPVs) are primary candidates for economical and flexible next-generation solar electricity conversion devices. However, efficiencies of the OPVs are limited, among other reasons, by poor charge transport and limited acceptor materials. To overcome this, hybrid organic–inorganic solar cells have been proposed. In this study, the authors investigated the photovoltaic characteristics of hybrid amorphous silicon (a-Si:H) films with varying doping nature with poly(3-hexylthiophene) (P3HT) only and P3HT:phenyl-C61-butyric acid methyl ester (PCBM) bulk-heterojunction–based solar cells. Both intrinsic and doped a-Si:H films were used. Despite the higher short circuit current density of P3HT/intrinsic a-Si:H device, the charge collection and open circuit voltage in P3HT/n+ a-Si:H device were the highest. This was attributed to favorable band bending and high built-in electric field in P3HT. Previously proposed model for photovoltaic mechanism in polymer/a-Si:H devices was revisited, and a revision was proposed. P3HT:PCBM cells on the three types of cells largely followed the same trend as the P3HT-only devices, except that intrinsic device did not have a photocurrent contribution from the organic layer.