Spectroelectrochemistry was used to study the electron trapping and rectifying behavior in several diphenylamine endgroup polymeric bilayers. Various combinations of the following monomers were pairwise sequentially electropolymerized onto ITO transparent electrodes: FD, DNTD, DPTD and Cl4DPTD. Poly(FD) is a p-type material while poly(DNTD), poly(DPTD) and poly(Cl4DPTD) are bipolar materials being both n-type and p-type. Bilayers of ITO|poly(FD)|poly (DNTD) or ITO|poly (FD)|poly (DPTD), block electrons from reducing the outer layer even at -1.0 V vs Ag/AgCl, yet holes effectively oxidize both layers. The LUMO differences between poly(DNTD) and poly(Cl4DPTD) or poly(DPTD) and poly(Cl4DPTD) provide a large enough electronic barrier that electron trapping can occur between these n-type materials. The visible spectra results imply that these polymers, poly(DPTD) or poly(Cl4DPTD) can be used as photovoltaic materials.