延伸二維共軛高分子側鏈結構之作用及其 應用於總體異質接面高分子太陽能電池之討論

Abstract

在此研究中，為了探討延伸側鏈結構對二維共軛高分子的影響，我參考實驗室學長合成的PBDTTBO (P1)高分子，合成出五種不同結構的予體－受體型共軛高分子。分別為P2(PBDTOEHBO)、P3(PBDTTEHBO)、P4(PBDTBTEHBO)、P5(PBDTTPEHBO)、P6(PBDTTTEHBO)在電子予體(donor) 部分我用了幾種不同結構的2D-BDT，並設計新的電子受體 (acceptor) 材料做搭配。再進行高分子物理與化學性質、光電特性、堆疊結構以及表面形貌分析比較。 其中P5、P6的吸光範圍較廣，這個結果顯示，在高分子主鏈上延伸共軛側鏈形成二維共軛結構，可以提升光吸收特性，使吸光範圍增廣並有效利用太陽光。製成元件後，P5、P6開路電壓(Voc)分別為0.88V與0.79V，短路電流(Jsc)分別為11.04 mA/cm2與11.56 mA/cm2，光電轉換效率(PCE): P5為4.3%、P6為4.8%。 與材料發展與文獻回顧中的研究比較，高分子電子予體結構與P4、P5、P6相似，在搭配不同的電子受體時，光電轉換效率分別可達到6.5%、7.3%、7.4%，代表這幾種電子予體有潛力進一步優化使光電轉換效率提升。可以設計其他的結構高分子電子受體 (acceptor) 搭配P4-P6的電子予體，或是調整溶劑的選擇，提高材料混合後的互溶性，以及元件製程時採用退火處理 (annealing) 的方式，增加材料的結晶性，提升電荷傳導性。

In this study, in order to explore extended side chain structure effects on two dimensional conjugated polymer, a series of donor－acceptor (D－A) conjugated polymers: P2(PBDTOEHBO)、P3(PBDTTEHBO)、P4(PBDTBTEHBO)、P5(PBDTTPEHBO)、P6(PBDTTTEHBO) were synthesized. In the polymer, several different structures of two dimensional -BDT were used as donor building block, and a new structure of acceptor building block was designed. The physical, chemical, photovoltaic, structural packing, and morphological properties of polymers were characterized in this research. Among these polymers, P5、P6 exhibit wider UV−vis absorption range. This result clearly indicates that the light-harvesting properties of the parent conjugated polymers could be improved by introducing chromophoric side chains to broaden its absorption range and maximize overlap with the solar emission spectrum. The organic solar cell open circuit voltage (Voc) of P5、P6 are 0.88V and 0.79V respectively, and the shortcut current (Jsc) are 11.04 mA/cm2 and 11.56 mA/cm2 respectively. The power conversion efficiency (PCE) of P5 achieves 4.3%, P6 achieves 4.8%. The power conversion efficiency can be further improved through designing other structures of acceptor, selecting suitable solvent to enhance polymer solubility, and increasing crystallinity by thermal annealing.