10 Décembre – Thesis defense - Bruno Flament

09 h30 Amphi 1 - Bordeaux INP ENSCBP (Pessac)

Design, fabrication and characterization of organic photodetectors for the near infra-red.

This thesis shows the study of different organic semiconductors and their use in organic photodetectors (OPDs). Their goal is the detection of light in the near infrared region. First, we presented a bibliographic study and a description of the working principles of OPDs. Then, we show a brief overlook of the optical and electrical properties of these materials and our selection of materials for the following study. In the main part of the study, we described the optimisation of these materials based on a reference for the fabrication and characterization process previously used for PCDTBT based OPDs. The optimization is done in multiple steps. Firstly, we decided the D:A combination present in the active layer. Then, we defined the OPDs architecture with respect to the electrodes and interfacial layers. Further optimization of the active layer in terms of D:A ratio, solvents, additives and annealing is presented. As a result, we obtained OPDs detecting light at 850 nm. The On/Off ratio reach values above 4.103 and responsivity as high as 0,15 A/W. We observed a strong impact of the phase separation in the bulk on responsivity. Finally, we described OPDs with an active layer composed of materials originating only from the project.

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