Simulation of the degradation behavior of small-molecule solar cells based on p-DTS(FBTTh2)2 as the donor material

Abstract The use of organic solar cells (OSCs), particularly those based on small-molecule materials, has gained recognition as being promising in photovoltaic applications. However, despite notable advances, persistent challenges in relation to the long-term stability and energy-conversion efficiency of these materials continue to pose significant obstacles to their widespread adoption. The aim of this study was to enhance the efficiency and durability of such cells under ambient conditions. To elucidate whether cells with small-molecule donor materials provide higher benefits and opportunities than cells with polymer donor materials, this study compares the electrical parameters of cells with both types of donor materials. OSCs based on 7,7′-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene-2,6-diyl)bis(6-fluoro-4-(5′-hexyl-[2,2′-bithiophene]-5-yl)benzo[c][1,2,5]thiadiazole): [6,6]-Phenyl C71 butyric acid methyl ester (p-DTS(FBTTh 2 ) 2 :PC 70 BM) and Poly [[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]: [6,6]-Phenyl C71 butyric acid methyl ester (PTB7:PC 70 BM) were manufactured and their electrical characteristics under ambient conditions determined after various time intervals. Numerical simulations based on the metal–insulator–metal (MIM) model were then performed to optimize the performance of the cells and to analyze their internal electrical dynamics in detail. The findings of this study reveal a direct relationship between solar cell degradation and the anode interface, thus enhancing understanding of the degradation mechanisms that occur in OSCs.