Novel BODIPY Derivatives Based Small Molecule Photovoltaic Materials:Synthesis And Performance Research

Green energy and sustainable development are two major task faced by mankind in the 21 st century. Photovoltaic became an important technology in the development of green energy. Small molecular based organic solar cells have attract more and more attentions in recent years due to their many merits, including accurate molecular structure, low cost, flexible, the simple preparation process and easy to realize large-scale preparation.BODIPY dyes are considered to be potential donor materials, due to their high stability, good tailoring, high molar extinction coefficients and high oxidation potentials, and the BODIPY derivatives have attract much attentions in the field of organic solar cells in recent years. Ziessel, Misra and Xiaobin Peng have done many impressive works, and gained some appealing achievements. However, BODIPY derivatives based small molecular donors are limited by the type sole of structures and the lack of sample quantities. The efficiency of ever reported BODIPY derivatives based solar cells are under 3%. Hence, enrichment of this type of materials and development tof high efficienct solar cells are very important.In order to address above issues, several types of novel BODIPY derivatives based small molecular donors were constructed in this thesis. Their thermal stabilities, photophysical properites and electrochemical behaviors were systematically studied. The relationships between the molecular structures and their properties were revealed. And photovoltaic performances were explored to insight their applications in solar cells. The major research contents of this thesis are listed below.1. We firstly synthesized 5 novel 3,5-positions electron donating unites substituent meso-thiophene BODIPY derivatives BDP1-5. These BODIPY derivatives exhibit panchromatic absorption with high extinction coefficients. The efficiency of organic solar cell device based on BDP1-5 and PC61 BM are 2.99%, 3.71%, 1.96%, 1.03% and 2.52%, respectively. Among them, the devise efficiency of BDP2 is close to the highest level of the same type of molecules.2. For intensively study meso- substituents affect on their photovoltaic performances, we synthesized four novel 3,5-positions electron donating unites substituent mesotriphenylamine BODIPY derivatives BDP6-9 and systematically studied their optical, electrical, and thermal properties. The results showed that meso- triphenylamine substituent have little influence on their optophysical photoelectric properties. The efficiency of devise based on BDP6-9 and PC61 BM are 0.76%, 1.00%, 1.68% and 1.93%, which are lower than the meso-thiophene substituent ones. This may due to the dihedral angle between triphenylamine and BODIPY core restrict the intermolecular charge transfer(ICT) and intermolecular energy transfer.3. In the third charpt, four D-A-D type BODIPY derivatives BDP10-13 were synthesized. Their optical, electrical, and thermal properties were systemtically studied. The influence of various eletron donating units on their properties was indepth analyzed. The results show that BDP10-13 exhibit panchromatic absorption with high extinction coefficients. The Stokes shifts of these compouds up to 1200 cm-1, and the fluorescence quantum yields of these compounds at low level. The hole mobilities of BDP10-13 are between 3.11 × 10-5 cm2 V-1 s-1 to 6.35 × 10-4cm2 V-1 s-1. Among them, BDP 11 is of the highest hole mobility. Furthermore, AFM result reveal that BDP11 have a good miscibility with PC61 BM. Under the optimal conditions, the efficiency of these BDP10-13/PC61 BM based devices are 1.49%, 2.15%, 1.06% and 1.56%, respectively.4. For investigate the synergy of diffiernt electron donating units affect on the properties in D-A-D type BODIPY derivatives. We firstly synthesized a serial of asymmetric D1-A-D2 type BODIPY derivatives BDP14-16. The efficiency of BDP14-16/PC61 BM based devices are between 1.15%-1.98%. These values are comparable to or surpass the symmetric ones, and this type of BODIPY derivatives show good potential applications.5. A serial of A-D-A type BODIPY derivatives(BDP17-19) featuring electron donating units linked with 2- positions of BODIPY core were synthesized. The absorption of BDP17-19 range of 300-700 nm. Due to the π–π stacking, a broader absorption bands with absorption thresholds over 800 nm were observed in the solid state. The device efficiency based on BDP17-19 and PC61 BM are 2.18%, 3.51% and 3.24%, respectively, which are of a high level in BODIPY based devices.