A novel low‐bandgap conjugated polymer (PTPTB, Eg = ∼ 1.6 eV), consisting of alternating electron‐rich N‐dodecyl‐2,5‐bis(2′‐thienyl)pyrrole (TPT) and electron‐deficient 2,1,3‐benzothiadiazole (B) units, is introduced for thin‐film optoelectronic devices working in the near infrared (NIR). Bulk heterojunction photovoltaic cells from solid‐state composite films of PTPTB with the soluble fullerene derivative [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) as an active layer shows promising power conversion efficiencies up to 1 % under AM1.5 illumination. Furthermore, electroluminescent devices (light‐emitting diodes) from thin films of pristine PTPTB show near infrared emission peaking at 800 nm with a turn on voltage below 4 V. The electroluminescence can be significantly enhanced by sensitization of this material with a wide bandgap material such as the poly(p‐phenylene vinylene) derivative MDMO‐PPV.

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Photoinduced trans−cis−trans isomerization, optical storage, and surface relief gratings are demonstrated in mixed Langmuir−Blodgett (LB) films of poly[4‘-[[2-(methacryloyloxy)ethyl]ethylamino]-2-chloro-4-nitroazobenzene] (HPDR13) and cadmium stearate (CdSt). The trans−cis−trans photoisomerization of the azobenzene chromophores from HPDR13 in the mixed LB film was achieved with a circularly polarized laser light. The birefringence induced by a linearly polarized laser light decreased with the number of layers and increased with the weight percentage of HPDR13 in the mixed LB film. The surface relief gratings recorded by exposing the mixed LB film to an interference pattern produced by the laser light were visualized through atomic force microscopy (AFM). Interestingly, it seems that the nonphotoactive CdSt domains have also migrated along with HPDR13 while recording the surface relief gratings.