Combined effects of space charge and energetic disorder on photocurrent efficiency loss of field-dependent organic photovoltaic devices. (9th October 2015)

• Record Type: Journal Article
• Authors: Yoon, Sangcheol; Park, Byoungchoo; Hwang, Inchan
• Is Part Of: Journal of physics. Volume 48:Number 44(2015)
• Publication Date: 2015-10-09
• Subjects: organic solar cells -- drift-diffusion model -- energetic disorder -- space-charge effects -- device physics; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/48/44/445106
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: The loss of photocurrent efficiency by space-charge effects in organic solar cells with energetic disorder was investigated to account for how energetic disorder incorporates space-charge effects, utilizing a drift-diffusion model with field-dependent charge-pair dissociation and suppressed bimolecular recombination. Energetic disorder, which induces the Poole–Frenkel behavior of charge carrier mobility, is known to decrease the mobility of charge carriers and thus reduces photovoltaic performance. We found that even if the mobilities are the same in the absence of space-charge effects, the degree of energetic disorder can be an additional parameter affecting photocurrent efficiency when space-charge effects occur. Introducing the field-dependence parameter that reflects the energetic disorder, the behavior of efficiency loss with energetic disorder can differ depending on which charge carrier is subject to energetic disorder. While the energetic disorder that is applied to higher-mobility charge carriers decreases photocurrent efficiency further, the efficiency loss can be suppressed when energetic disorder is applied to lower-mobility charge carriers.