Synthesis And Properties Of Organic Photovoltaic Materials Based On Polymers And Oligomers Of D-A Structure

Organic solar cells (OSCs) have drawn great interest since they possess uniqueadvantages such as low cost, light-weight and good mechanical flexibility.In this paper we designed and synthesized a series of polymers and small organicmolecules as donor materials for organic solar cells. The polymers (P1, P2, P3, P4andP5) were synthesized by different electron donor units and electron withdrawing units.Small organic molecules with A-D-A (D=donor, A=acceptor) structure, namely, S1,S2, S3, S4, S5, S6, S7, S8, S9and S10. Systematic studied thermal properties,photophysical properties, electrochemical properties and photovoltaic properties ofthe materials. The main results are as follows:1. Five copolymers (P1, P2, P3, P4and P5), containing3,4-dintro-thiophene ordithienosilole or benzodithiophene or thienopyrrolodione (TPD), have beensynthesized. The study results showed that P3copolymerized by dithienosilole andTPD has a wider absorption spectrum. P5copolymerized by dithienosilole andbenzodithiophene has better film-forming properties. The PCE of P3and P5basedbulk heterojunction organic solar cells are2.75%and2.12%, respectively.2. Fore small organic molecules (S1, S2, S3and S4) with A-D-A structurecontaining dithienosilole (D) and octyl cyanoacetate (A) or dicyano (A), havedifferent substituent groups on thiophene bridges. The PCE of S1, S2, S3and S4based bulk heterojunction organic solar cells are3.28%,2.88%,0.26%and3.85%,respectively.3. Three small organic molecules (S5, S6and S7) with A-D-A structure containspirobifluorene (D) and benzothiadiazole, then malononitrile, octyl cyanoacetate and3-ethylrhodanine as different electron-withdrawing units at the end. The PCE of S5,S6and S7based bulk heterojunction organic solar cells are0.20%,0.10%and0.34%,respectively.4. Three small organic molecules (S8, S9and S10) with A-D-A structure containdiketopyrrolopyrrole (A) and spirobifluorene (D) or benzodithiophene (D) ordithienosilole (D). The PCE of S8, S9and S10based bulk heterojunction organicsolar cells are0.16%,1.69%and1.55%, respectively.