217-19-6Relevant articles and documents
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.
Development of novel naphtho[1,2-b:5,6-b′]dithiophene and thieno[3,4-c]pyrrole-4,6-dione based small molecules for bulk-heterojunction organic solar cells
Bagde, Sushil S.,Park, Hanok,Han, Jang-Gun,Li, Yinji,Ambade, Rohan B.,Ambade, Swapnil B.,Kim, ByeongCheol,Lee, Soo-Hyoung
, p. 117 - 125 (2016/10/26)
Two new small molecules, composed of naphthodithiophene (NDT) donor core and thienopyrroledione (TPD) group acceptor group end-capped with and without an alkyl-bithiophene, defined as NDT(TPD)2 and NDT(TPDTT)2 were designed and synthesized by stille coupling reactions. The thermal and electrochemical analyses carried out for both the small molecules revealed good thermal stability along with high decomposition temperature (>350?°C). NDT(TPD)2 showed a deep HOMO level (?5.38?eV), compared to slightly upshifted HOMO (?5.26?eV) of NDT(TPDTT)2. While X-ray diffractometry suggests crystalline and amorphous nature of NDT(TPD)2 and NDT(TPDTT)2 respectively, the space charge limited current analysis revealed high hole mobility in the former and appreciable charge balance in the later. The conventional organic solar cell (OSC) devices fabricated using NDT(TPD)2 and NDT(TPDTT)2 as donor show power conversion efficiency (PCE) of 0.26% and 0.8% respectively. While NDT(TPDTT)2 device after blending with additive, owing to the improved D-A heterojunction yielded maximum PCE of 1.31% resulting from enhanced Jsc 3.32?mA/cm2, Voc 0.75?V and FF of 52.44.
Modulation of electronic properties of π-conjugated copolymers derived from naphtho[1,2-b:5,6-b′]dithiophene donor unit: A structure-property relationship study
Dutta, Pranabesh,Park, Hanok,Oh, Minjae,Bagde, Sushil,Kang, In Nam,Lee, Soo-Hyoung
, p. 2948 - 2958 (2013/07/27)
A set of three donor-acceptor conjugated (D-A) copolymers were designed and synthesized via Stille cross-coupling reactions with the aim of modulating the optical and electronic properties of a newly emerged naphtho[1,2-b:5,6-b′] dithiophene donor unit for polymer solar cell (PSCs) applications. The PTNDTT-BT, PTNDTT-BTz, and PTNDTT-DPP polymers incorporated naphtho[1,2-b:5,6- b′]dithiophene (NDT) as the donor and 2,2′-bithiazole (BTz), benzo[1,2,5]thiadiazole (BT), and pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DPP), as the acceptor units. A number of experimental techniques such as differential scanning calorimetry, thermogravimetry, UV-vis absorption spectroscopy, cyclic voltammetry, X-ray diffraction, and atomic force microscopy were used to determine the thermal, optical, electrochemical, and morphological properties of the copolymers. By introducing acceptors of varying electron withdrawing strengths, the optical band gaps of these copolymers were effectively tuned between 1.58 and 1.9 eV and their HOMO and LUMO energy levels were varied between -5.14 to -5.26 eV and -3.13 to -3.5 eV, respectively. The spin-coated polymer thin film exhibited p-channel field-effect transistor properties with hole mobilities of 2.73 × 10-3 to 7.9 × 10-5 cm2 V-1 s-1. Initial bulk-heterojunction PSCs fabricated using the copolymers as electron donor materials and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as the acceptor resulted in power conversion efficiencies in the range of 0.67-1.67%.
