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In‐depth understanding of photocurrent enhancement in solution‐processed small‐molecule:perylene diimide non‐fullerene organic solar cells
Author(s) -
Chen Yuxia,
Zhang Xin,
Zhan Chuanlang,
Yao Jiannian
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201532102
Subject(s) - perylene , photocurrent , diimide , acceptor , organic solar cell , materials science , photoactive layer , fullerene , energy conversion efficiency , optoelectronics , absorption (acoustics) , solar cell , polymer solar cell , chemical physics , chemistry , molecule , physics , organic chemistry , composite material , condensed matter physics , polymer
The experimental current is scaled by the generation, transportation and recombination loss of the mobile carriers. In this paper, we show that a change of small molecule/perylene diimide (PDI) weight ratio from 1:1 to 3:1 does not lead to different transportation or different recombination loss in the solar cell, while it results in different generation of the mobile 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 ability than the PDI acceptor. With respect to the contribution from the enhancement of the absorption of the solar photons, our data demonstrate that the phase size of the acceptor (donor) 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 ( J SC ) and phase size of the acceptor domains. Through fine‐tuning the D/A ratio, the best compatibility between the small molecule donor and the PDI acceptor is obtained at a mediate D/A ratio of 1.3:1, at which the absorbed solar photons are exploited efficiently, yielding an average power conversion efficiency of over 5.07 ± 0.10%. Compatibility and charge separation are modulated by varying donor weight ration in small molecule donor:perylene diimide based non‐fullerene solar cells, which affords improved exploitation of the solar photons absorbed by the photoactive layer. The acceptor phase size is a key factor that scales the photocurrent. An efficiency of 5.1% is obtained from this non‐fullerene small molecule system as a result of modulation of compatibility.