In-depth understanding of photocurrent enhancement in solution-processed small-molecule:perylene diimide non-fullerene organic solar cells

The experimental current is scaled by the generat o transportation (Ind recomhination loss of the mohile carriers. In this paper. We show that a change ol small molecule/ perylene diimide (PDI) weight ratio from I:I to 3:1 does not lead to different transportation or different recombination loss in the solar cell. while it results in different ge en at ion of the mohi le carriers. With the increase of the donor/acceptor (D/A) ratio. the blend film has an enhanced absorption because the donor has a stronger light-harvesting ahility than the P1 acceptor. With respect to the contrihution from the enhancement of the absorption of the solar photons. our data demonstrate that the phase site of the acceptor Holton domains is the key factor that determines the generation of the mobile carriers. We observe a good relationship between the average short-circuit current density (m 1 and phase site of the acceptor domains. Through line-tuning the D/A ratio. the hest compatihility hemeen the small molecule donor and the PD1 acceptor is ohtained at a mediate D/A ratio of 1.3:1. at which the absorbed solar photons are exploited el hciently. yielding an average power conversion efficiency of over Compatihility and charge sep(tration are modulated hy Vary i ng donor weight ration in small molecule donorperylene diimide hased non-fullerene solar cells. NVI1 al101dS improved exploitation of the solar photons absorbed by the photoactive layer. The acceptor phase site is a Rey Iactor that scales the photocurrent. An efficiency of 5.1 is ohtained from this non-fullerene small molecule system as a result of modulation of compatibility. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim