Browsing by Author "Lin, You-Wei"

Now showing 1 - 3 of 3

A chlorinated nonacyclic carbazole-based acceptor affords over 15% efficiency in organic solar cells
(2020-01-21)
Chen, Tsung-Wei
;
Peng, Kuan-Lin
;
Lin, You-Wei
;
Su, Yi-Jia
;
Ma, Ko-Jui
In this contribution, a dithienocyclopentacarbazole (DTC)-based and two dithieno[3,2-b]thiophenecyclopentacarbazole (DTTC)-based non-fullerene acceptors (NFAs) named DTC-4F, DTTC-4F and DTTC-4Cl were exploited to elucidate the effects of conjugation extension and end group chlorination. DTTC-4F was designed through conjugation extension on the basis of DTC-4F by fusing one additional thiophene on both flanks of the heptacyclic DTC core, generating the nonacyclic DTTC core. Compared with DTC-4F, DTTC-4F features up-shifted energy levels, red-shifted absorption and enhanced pi-pi interaction. PM6:DTTC-4F exhibits a decent PCE of 13.89% with a V-OC of 0.95 V, a J(SC) of 21.66 mA cm(-2) and a FF of 67.60%. Although DTTC-4F affords a reduced FF compared to DTC-4F, a DTTC-4F-based device delivers a higher PCE than DTC-4F-based devices due to the extended absorption range of DTCC-4F in comparison with DTC-4F. Since chlorinated NFAs are known to possess stronger pi-pi interaction than fluorinated NFAs, DTTC-4Cl was therefore synthesized by end-capping DTTC core with 2Cl-IC groups instead of 2F-IC groups. Moreover, DTTC-4Cl demonstrates a red-shifted absorption in comparison with DTTC-4F, which is beneficial for light-harvesting. Overall, PM6:DTTC-4Cl affords an outstanding PCE of 15.42% with a V-OC of 0.92 V, a J(SC) of 22.64 mA cm(-2) and a FF of 74.04%, which is the record PCE observed in carbazole-based NFAs.
Chlorinated Carbon-Bridged and Silicon-Bridged Carbazole-Based Nonfullerene Acceptors Manifest Synergistic Enhancement in Ternary Organic Solar Cell with Efficiency over 15%
(1970-01-01)
Chen, Tsung-Wei
;
Yu, Jun-Yan
;
Lin, You-Wei
;
Peng, Shih-Hao
;
Wu, Shang-Hsuan
Herein, two novel nonfullerene acceptors (NFAs), DTCC-4Cl and DTSiC-4Cl, are synthesized by end-capping dithienocyclopentacarbazole (DTCC) and dithieno-silolocarbazole (DTSiC) cores with chlorinated IC (2Cl-IC) units, respectively. With the better-known advantage of having the extraordinary sigma*-pi* conjugation of silole unit embedded in the DTSiC core, DTSiC-4Cl manifests upshifted lowest unoccupied molecular orbital (LUMO), blue-shifted absorption, and increased pi-pi interaction in comparison with DTCC-4Cl. Furthermore, to elucidate the effect of bridging atoms on the photovoltaic performance, T1 is selected as the polymer donor to be blended with DTCC-4Cl and DTSiC-4Cl. T1:DTCC-4Cl-based devices exhibit a fine power conversion efficiency (PCE) of 14.43% and T1:DTSiC-4Cl-based devices exhibit a comparable PCE of 14.46%. Interestingly, the T1:DTSiC-4Cl-based devices demonstrate an additive-free feature, which is worthy of further applications. From the perspective of constructing high-performance ternary devices, DTCC-4Cl is expected to possess excellent compatibility with DTSiC-4Cl owing to its structural similarity. As anticipated, the ternary T1:DTSiC-4Cl:DTCC-4Cl-based device outperforms the binary T1:DTCC-4Cl and T1:DTSiC-4Cl-based devices, affording a decent PCE of 15.04% with aV(OC)of 0.97 V, aJ(SC) of 20.80 mA cm(-2), and an FF of 74.55% without any additive.
Fluorinated heptacyclic carbazole-based ladder-type acceptors with aliphatic side chains for efficient fullerene-free organic solar cells
(2019-05-01)
Chen, Tsung-Wei
;
Hsiao, Yu-Tang
;
Lin, You-Wei
;
Chang, Chia-Chih
;
Chuang, Wei-Tsung
Molecular engineering of non-fullerene acceptors (NFAs) is a promising strategy to uncover new structure-property relationships and design principles for developing next-generation high performance n-type materials. Two dithienocyclopentacarbazole (DTC)-based NFAs, DTC(4R)-IC and DTC(4R)-4FIC, are synthesized to elucidate the effects of incorporating aliphatic side chains and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) end groups on the thermal and optoelectronic properties of these NFAs. An inverted organic solar cell architecture of ITO/ZnO/J71:NFA/MoO3/Ag is employed. By replacing the phenyl-based side chains with aliphatic side chains on the carbon bridges of the carbazole-based core, the device containing DTC(4R)-IC exhibits an enhanced PCE of 9.61%, a V-OC of 0.94 V, a J(SC) of 16.44 mA cm(-2), and a FF of 62.00%, whereas the device containing DTC(4Ph)-IC exhibits a PCE of 7.76%. The incorporation of 2FIC end groups affords DTC(4R)-4FIC featuring better device performance relative to DTC(4R)-IC, a more red-shifted absorption edge, and a broader absorption range upon fluorination. Notably, the device fabricated with DTC(4R)-4FIC affords a V-oc of 0.82 V, a J(sc) of 18.92 mA cm(-2), a FF of 70.22% and a highest PCE of 10.89%, which is by far the highest PCE for NFA containing heptacyclic carbazole cores.