4891-44-5Relevant articles and documents
13.4 % Efficiency from All-Small-Molecule Organic Solar Cells Based on a Crystalline Donor with Chlorine and Trialkylsilyl Substitutions
Su, Wenyan,Wang, Yang,Yin, Zhihong,Fan, Qunping,Guo, Xia,Yu, Liyang,Li, Yuxiang,Hou, Lintao,Zhang, Maojie,Peng, Qiang,Li, Yongfang,Wang, Ergang
, p. 3535 - 3543 (2021/06/25)
How to simultaneously achieve both high open-circuit voltage (Voc) and high short-circuit current density (Jsc) is a big challenge for realising high power conversion efficiency (PCE) in all-small-molecule organic solar cells (all-SM OSCs). Herein, a novel small molecule (SM)-donor, namely FYSM?SiCl, with trialkylsilyl and chlorine substitutions was designed and synthesized. Compared to the original SM-donor FYSM?H, FYSM?Si with trialkylsilyl substitution showed a decreased crystallinity and lower highest occupied molecular orbital (HOMO) level, while FYSM?SiCl had an improved crystallinity, more ordered packing arrangement, significantly lower HOMO level, and predominant “face-on” orientation. Matched with a SM-acceptor Y6, the FYSM?SiCl-based all-SM OSCs exhibited both high Voc of 0.85 V and high Jsc of 23.7 mA cm?2, which is rare for all-SM OSCs and could be attributed to the low HOMO level of FYSM?SiCl donor and the delicate balance between high crystallinity and suitable blend morphology. As a result, FYSM?SiCl achieved a high PCE of 13.4 % in all-SM OSCs, which was much higher than those of the FYSM?H- (10.9 %) and FYSM?Si-based devices (12.2 %). This work demonstrated a promising method for the design of efficient SM-donors by a side-chain engineering strategy via the introduction of trialkylsilyl and chlorine substitutions.
BODIPY based A-D-A molecules: Effect of CF3 group substitution at meso phenyl group
Johnson, Justin C.,Larson, Bryon W.,Ramamurthy, Praveen C.,Tarafdar, Gourav
, (2020/03/06)
Two pairs of A-D-A molecules have been synthesized with fluorene and benzodithiophene as the central donor subunits and terminal BODIPY units, functionalized with either a 4-methylphenyl or 4-trifluoromethylphenyl group at the meso position. The effect of the para substituent of the meso phenyl group on the photophysical properties of these molecules is studied through steady state absorption and fluorescence spectroscopy as well as femtosecond transient absorption and time resolved fluorescence spectroscopy techniques. Applicability of these molecules as donors in solution processed solar cell active layers was investigated through time resolved microwave conductivity measurements on blends with PC60BM acceptor, which shows a varying yield of charge transfer with choice of substituent. Transient absorption spectroscopy is then employed to investigate the role of the 4-trifluoromethylphenyl group in altering the efficiency of charge transfer from these A-D-A molecules to PC60BM. The results show a consistent picture of picosecond charge transfer and a component of a few hundred ps geminate recombination that results in a small yield of long-lived free charges optimized for the methylphenyl derivatives.
A new 2D-naphtho[1,2-b:5,6-b']dithiophene based donor small molecules for bulk-heterojunction organic solar cells
Bagde, Sushil S.,Park, Hanok,Tran, Van-Huong,Lee, Soo-Hyoung
, p. 30 - 39 (2018/11/30)
We present design and synthesis of three new symmetrical and linear A-D-A type π-conjugated donor small molecules (2D-NDT(TPD)2, 2D-NDT(Ester)2 and 2D-NDT(Amide)2) containing two dimensional (2D) naphthodithiophene (NDT) unit as the central donor core, end-capped with electron deficient unit such as thieno[3,4c]pyrrole-4,6-dione (TPD), 2-ethylhexyl 2-cyanoacetate (Ester) and 2-cyano-N-(2-ethylhexyl)acetamide (Amide) group respectively. We characterized these small molecules and further investigated the optical, electrochemical, morphological and photovoltaic properties. When solution–processed bulk heterojunction organic solar cells are fabricated using these small molecules, the morphology of 2D-NDT(Ester)2 or 2D-NDT(Amide)2 and [6,6]-PhenylC71-butyric acid methyl ester (PC71BM) blend film was optimized using 1,8 Diiodooctane (DIO) additive. DIO additive promotes the formation of nanoscopically well-connected molecular domains in the active blend film. A device based on (1% DIO, 1:1) 2D-NDT(Ester)2:PC71BM exhibited highest the efficiency of 1.22% with a short-circuit density (Jsc) of 3.75 mA/cm2, an open circuit voltage (Voc) of 0.91 V and fill factor (FF) of 35.50. Similarly for (1% DIO, 1:3) 2D-NDT(Amide)2:PC71BM device efficiency of 0.55%, with Jsc of 2.36 mA/cm2, Voc of 0.64 V and FF of 36.95 was observed. Whereas for (1:2) 2D-NDT(TPD)2:PC71BM device, due to the improper blending and phase separation between donor and acceptor efficiency restricted to 0.33% with Jsc of 1.66 mA/cm2, Voc of 0.73 V and FF of 27.2.
