Effect of charge trapping on geminate recombination and polymer solar cell performance.
In this letter, we examine the effect of charge trapping on geminate recombination and organic photovoltaic performance using a Monte Carlo model. We alter the degree of charge trapping by considering energetic disorder to be spatially uncorrelated or correlated. On correlating energetic disorder, and so reducing the degree of trapping, it is found that power conversion efficiency of blend and bilayer devices improves by factors of 3.1 and 2.6, respectively. These results are related to the experimental data and quantum chemical calculations for poly[9,9-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine] (PFB)/poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as well as poly(3-hexylthiophene) (P3HT)/(6,6)-phenyl-C(61)-butyric acid methyl ester (PCBM) solar cell systems. The minimization of traps at the heterojunction between electron- and hole-accepting materials, perhaps by molecular design, appears to be a promising strategy to achieve large gains in PV performance. It is also shown that macroscopically measurable quantities such as mobility and energetic disorder are not necessarily good predictors of nanoscale geminate recombination process.
Cavendish Laboratory, Cambridge University, J.J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom. Chris.Groves@Durham.ac.uk.
Chris
C
Groves
James C
JC
Blakesley
Neil C
NC
Greenham
D017076:Computer-Aided Design; D011211:Electric Power Supplies; D004579:Electron Transport; D004867:Equipment Design; D019544:Equipment Failure Analysis; D009010:Monte Carlo Method; D011108:Polymers / Q000737:chemistry*; D012993:Solar Energy; D055672:Static Electricity
D011108:Polymers