Porphyrins and BODIPY as Building Blocks for Efficient Donor Materials in Bulk Heterojunction Solar Cells

Abstract

International audienceAdvances in the synthesis and application of highly efficient polymers and small molecules over the last two decades have enabled the rapid advancement in the development of organic solar cells and photovoltaic technology as a promising alternative to conventional solar cells, based on silicon and other inorganic semiconducting materials. Among the different types of organic semiconducting materials, porphyrins and BODIPY-based small molecules and conjugated polymers attract high interest as efficient semiconducting organic materials for dye sensitized solar cells and bulk heterojunction organic solar cells. The highest power conversion efficiency exceeding 9% has been reported so far for porphyrin small molecules and 8.60% for conjugated polymers based on porphyrins. On the other hand, small molecules and conjugated polymers based on BODIPY moiety have been successfully used as donor materials for solution processed bulk heterojunction organic solar cells, and the resultant devices showed power conversion efficiencies exceeding 5.5%. In this article, the development of molecular design of porphyrins and BODIPY small molecules and polymers for bulk heterojunction organic solar cells are reviewed, and a guideline for the structure-performance relationship is provided

High-yielding Pd2(dba)3·C6H6-based four-fold Sonogashira coupling with selenophene-conjugated magnesium tetraethynylporphyrin for organic solar cells

“…Solution-processed small-molecule (SM) bulk-heterojunction (BHJ) organic solar cells (OSCs) have attracted much greater attention in the past several years due to the revolutionary improvements seen in their power conversion efficiency (PCE). [1][2][3][4][5][6] To date, PCEs when using SMs have exceeded 9-14% in single-junction BHJ OSCs as a result of efforts in material innovation and device optimization. [7][8][9][10][11][12][13][14][15][16][17] Among the useful donor (D)-acceptor (A) materials, porphyrins with a structure of D-(p-A) 2 and D-(p-A) 4 conjugated with electron-decient groups at the meso-positions via ethynyl bridges exhibit outstanding performance.…”

“…For example, the extensive conjugation and large molecular geometry tend to result in excessive rigidity, leading to poor solubility, which is unfavorable for device fabrication and synthesis procedures. 30 A narrow band gap (low energy loss) and broad absorption (high short-circuit current density, J SC ) can be easily achieved by the strategy of increased intramolecular charge transfer with the D-(p-A) 2 and D-(p-A) 4 structures, but this alone does not guarantee high PCEs because there could still be energy level mismatch between the HOMO of the electrondonor material and the LUMO of the electron-acceptor material. 30 To obtain high open-circuit voltage (V OC ), energy level matching and as high a HOMO level of donor material as possible are essential.…”

“…60 Based on the above considerations and existing challenges, we are interested in systematically exploring the effects of selenium substitution and end-capping with alkyl chains of thiophenes on the photovoltaic performance of SMs with D-(p-A) 4 and D-(p-A-Ar) 4 frameworks. In this work, we designed and synthesized three p-conjugated donor molecules based on a Mg-porphyrin core with four Se-DPP units with or without alkyl-thiophenes end-caps, namely, Mg-TEP-(Se-DPP) 4 , Mg-TEP-(S-DPP-Th) 4 and Mg-TEP-(Se-DPP-Th) 4 (TEP ¼ magnesium tetraethynyl porphyrin). Importantly, we developed a new catalytic system of Pd 2 (dba) 3 $(C 6 H 6 )/PPh 3 /CuI to effectively suppress porphyrin homocoupling by-products and increase the yield of the desired molecules, such as Mg-TEP-(Se-DPP) 4 (2a, 80% yield), obtained from Sonogashira coupling.…”

“…We found that Mg-TEP-(Se-DPP) 4 (2a) exhibited the following characteristics in comparison with previously reported Mg-TEP-(S-DPP) 4 (3a), (a) a narrower band gap; (b) more closely matched energy levels, (c) extensive absorption in both the ultraviolet and visible-NIR regions, and (d) slightly poorer morphology of blended lms. Moreover, Mg-TEP-(S-DPP-Th) 4 and Mg-TEP-(Se-DPP-Th) 4 have excellent solubility. Ultimately, Mg-TEP-(Se-DPP) 4 showed a decent PCE of 6.09% and photoresponse up to 1000 nm ( Fig.…”

“…Moreover, Mg-TEP-(S-DPP-Th) 4 and Mg-TEP-(Se-DPP-Th) 4 have excellent solubility. Ultimately, Mg-TEP-(Se-DPP) 4 showed a decent PCE of 6.09% and photoresponse up to 1000 nm ( Fig. 1 and 2).…”