Influence of Annealing of PCDTBT:PC₇₀BM on the Performance of Polymer Solar Cells

Abstract

Bulk-heterojunction polymer solar cells (BHJ-PSCs) have attracted considerable attention because of their unique advantages of lightweight, low cost, mechanical flexibility and suitable for large-area fabrication [1–3]. In the last decades, much attention has been paid to the donor and acceptor system P3HT:PCBM, However, because of the relatively large bandgap of P3HT (∼1.9 eV) and the relatively small energy difference between the lowest unoccupied molecular orbital (LUMO) of PCBM and the highest occupied molecular orbital (HOMO) of P3HT, the photovoltaic performance of the PSCs based on P3HT:PCBM is still significantly lower than the inorganic solar cells. Recently more work has been done on the novel donor materials which have a reduced energy gap with an ability of harvesting more of the sun’s spectral emission and a high charge carriers mobility for charge transport. One of the most promising new donor polymer is poly [N-9"-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3' -benzothiadiazole)] (PCDTBT) with a HOMO level of 5.5eV which is 0.4 eV down-shifted than that of P3HT. When PCDTBT is blended with the fullerene acceptor PC70BM, it showed excellent photovoltaic performance with a power conversion efficiency of ∼ 6%. [6]

Pontos quânticos em células fotovoltaicas de terceira geração

“…Os materiais escolhidos para compor a camada ativa dessas células foram, o fulereno PCBM e os polímeros conjugados PCDTBT e P3HT. Esses materiais foram selecionados por serem eficientes quando aplicados em FV de terceira geração, chegando a valores de 6,1 % de eficiência [84] [85]. Dessa forma, foram construídas células com camada ativa de PCBM: PCDTBT e PCBM: P3HT e a estrutura geral das células foi: ITO/ PEDOT/ Camada Ativa/ Ca-Al (Figura 61).…”