The Electronic State Of 1ML PC₆₁BM/Ag（100）

We have briefly reviewed the development of the bulk heterojunction polymer solar cells, including their device structures, principles, materials of the donor and acceptor, etc. This new type of energy power has many advantages. However, because the as-acquired efficiency of energy conversion was relatively low, the solar cells encountered obstacles in the road towards commercial applications. Therefore, it was necessary to further study the factors restricting the efficiency of energy conversion.The electronic structure of the electrode interface is one of the factors which affects the efficiency of energy conversion. Ag is one of the common electrodes, and PC61BM is the most commonly used acceptor material. In this thesis, we used synchrotron radiation photoemission spectroscopy and X-ray absorption spectroscopy to study the electronic state of one monolayer PC61BM on the surface of Ag(100). We found that the work function of the 1 MLPC61BM/Ag(100) increased by 0.24 eV as compared to thick PC61BM film. There were electrons transferring from Ag(100) to PC61BM at the interface. In order to study its ability to accept more electrons, we doped the 1 ML PC61BM/Ag(100) with K atoms and found that PC61BM could accept a total of six electrons (including the electrons from the Ag(100) substrate). Taking the doping-saturated sample as the reference, we determined that the amount of charge transfer for the undoped 1 ML PC61BM/Ag(100) were 1.0—1.7 electrons. The binding energy of the exciton for PC61BM molecules was 0.6 eV Besides,1 ML PC61BM/Ag(100) exhibited metallic property.