Browsing by Author "Chu, Cheng-Che"

Now showing 1 - 4 of 4

A High-Mobility Low-Bandgap Copolymer for Efficient Solar Cells
(2010-12-15)
Ding, Ping
;
Chu, Cheng-Che
;
Liu, Bo
;
Peng, Bo
;
Zou, Yingping
A new high-mobility low-bandgap polymer, PBDT-DODTBT, based on benzodithiophene and 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl) benzothiadiazole has been synthesized through a standard Stille coupling reaction. The polymer is soluble in common organic solvents, such as chloroform, tetrahydrofuran, and chlorobenzene and has excellent film forming properties. Preliminary studies of the copolymer showed the charge mobility as high as 7.15 x 10(-3) cm(2).V(-1). s(-1) from SCLC measurement. Initial photovoltaic cells based on the composite structure of ITO/PEDOT: PSS/PBDT-DODTBT: (alpha)PC(71)BM (1:2)/Ca/Al showed an open-circuit voltage of 0.76 V, a power conversion efficiency of 4.02%, and a short-circuit current of 8.96mA.cm(-2).
Alternating and Diblock Donor-Acceptor Conjugated Polymers Based on Diindeno[1,2-b:2 ',1 '-d]thiophene Structure: Synthesis, Characterization, and Photovoltaic Applications
(2010)
Chen, Chiu-Hsiang
;
Cheng, Yen-Ju
;
Dubosc, Martin
;
Hsieh, Chao-Hsiang
;
Chu, Cheng-Che
Pentacyclic diindeno[1,2':2',1'-d]thiophene (DIDT) unit is a rigid and coplanar conjugated molecule. To the best of our knowledge, this attractive molecule has never been incorporated into a polymer and thus its application in polymer solar cells has never been explored. For the first time, we report the detailed synthesis of the tetra-alkylated DIDT molecule leading to its dibromo-and diboronic ester derivatives, which are the key monomers for preparation of DIDT-based polymers. Two donor-acceptor alternating polymers, poly(diindenothiophene-alt-benzothiadiazole) PDIDTBT and poly-(diindenothiophene-alt-dithienylbenzothiadiazole) PDIDTDTBT, were synthesized by using Suzuki polymerization. Copolymer PTDIDTTBT was also prepared by using Stille polymerization. Although PTDIDTTBT is prepared through a manner of random polymerization, we found that the different reactivities of the dibromo-monomers lead to the resulting polymer having a block copolymer arrangement. With the higher structural regularity, PTDIDTTBT, symbolized as (thiophene-alt-DIDT)(0.5)-block-(thiophene-alt-BT)(0.5), shows the higher degree of crystallization, stronger pi-pi stacking, and broader absorption spectrum in the solid state, as compared to its alternating PDIDTDTBT analogue. Bulk heterojunction photovoltaic cells based on ITO/PEDOT:PSS/polymer:PC(71)BM/Ca/Al configuration were fabricated and characterized. PDIDTDTBT/PC(71)BM and PTDIDTTBT/PC(71)BM systems exhibited promising power-conversion efficiencies (PCEs) of 1.65% and 2.00%, respectively. Owing to the complementary absorption spectra, as well as the compatible structures of PDIDTDTBT and PTDIDTTBT, the PCE of the device based on the ternary blend PDIDTDTBT/PTDIDTTBT/PC(71)BM was further improved to 2.40%.
Effects of thiophene units on substituted benzothiadiazole and benzodithiophene copolymers for photovoltaic applications
(2012-09-05)
Ding, Ping
;
Zou, Yingping
;
Chu, Cheng-Che
;
Xiao, Dequan
;
Hsu, Chain-Shu
Two conjugated copolymers, poly{4,7-[5,6-bis(octyloxy)]benzo(c)(1,2,5)thiadiazole-alt-4,8-di(2-ethylhexyloxyl)benzo[1,2-b:3,4-b]dithiophene} (P1) and poly(2-{5-[5,6-bis(octyloxy)-4-(thiophen-2-yl)benzo(c)(1,2,5)thiadiazol-7-yl] thiophen-2-yl}-4,8-di(2-ethylhexyloxyl)benzo(1,2-b:3,4-b)dithiophene) (P2), composed of benzodithiophene and 5,6-dioctyloxybenzothiadiazole derivatives with or without thiophene units were synthesized via a Stille cross-coupling polymerization reaction. These copolymers are promising for applications in bulk heterojunction solar cells because of their good solubility, proper thermal stability, moderate hole mobility, and low band gap. The photovoltaic properties of these copolymers were investigated on the basis of blends of the different polymer/(6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) weight ratios under AM1.5G illumination at 100 mW/cm2. The device with indium tin oxide/poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)/P2:PC71BM (1 : 2 w/w)/Ca/Al gave a relatively better photovoltaic performance with a power conversion efficiency of 1.55%. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
New Low Bandgap Conjugated Polymer Derived from 2, 7-Carbazole and 5, 6-Bis(octyloxy)-4, 7-di(thiophen-2-yl) Benzothiadiazole: Synthesis and Photovoltaic Properties
(2012-01-05)
Ding, Ping
;
Chu, Cheng-Che
;
Zou, Yingping
;
Xiao, Dequan
;
Pan, Chunyue
To develop conjugated polymers with low bandgap, deep HOMO level, and good solubility, a new conjugated alternating copolymer PC-DODTBT based on N-9'-heptadecanyl-2,7-carbazole and 5, 6-bis(octyloxy)-4,7di(thiophen-2-yl) benzothiadiazole was synthesized by Suzuki cross-coupling polymerization reaction. The polymer reveals excellent solubility and thermal stability with the decomposition temperature (5% weight loss) of 327 degrees C. The HOMO level of PC-DODTBT is -5.11 eV, indicating that the polymer has relatively deep HOMO level. The hole mobility of PC-DODTBT as deduced from SCLC method was found to be 2.03 x 10(-4) cm(2)/Versus Polymer solar cells (PSCs) based on the blends of PC-DODTBT and [6,6]-phenyl-C(71)-butyric acid methyl ester (PC(71)BM) with a weight ratio of 1:2.5 were fabricated. Under AM 1.5 (AM, air mass), 100 mW/cm(-2) illumination, the devices were found to exhibit an open-circuit voltage (V(oc)) of 0.73 V, short-circuit current density (J(sc)) of 5.63 mA/cm(-2), and a power conversion efficiency (PCE) of 1.44%. This photovoltaic performance indicates that the copolymer is promising for polymer solar cells applications. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 99-107, 2012