Pentacyclic diindeno[1,2‐b: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 π–π 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:PC71BM/Ca/Al configuration were fabricated and characterized. PDIDTDTBT /PC71BM and PTDIDTTBT /PC71BM 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 /PC71BM was further improved to 2.40 %. 相似文献
We have developed a ladder‐type dithienocyclopentathieno[3,2‐b]thiophene ( DTCTT ) hexacyclic unit in which the central thieno[3,2‐b]thiophene ring was covalently fastened to two adjacent thiophene rings through carbon bridges, thereby forming two connected cyclopentadithiophene ( CPDT ) units in a hexacyclic coplanar structure. This stannylated Sn‐DTCTT building block was copolymerized with three electron‐deficient acceptors, dibromo‐thieno[3,4‐c]pyrrole‐4,6‐dione ( TPD ), dibromo‐benzothiadiazole ( BT ), and dibromo‐phenanthrenequinoxaline ( PQX ), by Stille polymerization, thereby furnishing a new class of alternating donor–acceptor copolymers: PDTCTTTPD , PDTCTTBT , and PDTCTTPQX , respectively. Field‐effect transistors based on PDTCTTPQX and PDTCTTBT yielded high hole mobilities of 0.017 and 0.053 cm2 V?1 s?1, respectively, which are among the highest performances among amorphous donor–acceptor copolymers. A bulk heterojunction solar cell that incorporated PDTCTTTPD with the lower‐lying HOMO energy level delivered a higher Voc value of 0.72 V and a power conversion efficiency (PCE) value of 2.59 %. 相似文献
A new balanced donor–acceptor molecule, namely, benzodithiophene (BDT)‐rhodanine‐[6,6]‐phenyl‐C71 butyric acid methyl ester (Rh‐PC71BM) comprising two covalently linked blocks, a p‐type oligothiophene‐containing BDT‐based moiety and an n‐type PC71BM unit was designed and synthesized. The single‐component organic solar cell (SCOSC) fabricated from Rh‐PC71BM molecules showed a power conversion efficiency (PCE) of 3.22 % with an open‐circuit voltage (Voc) of 0.98 V. These results rank are among the highest values for SCOSCs based on a monomolecular material. In particular, the one‐molecule Rh‐PC71BM device exhibits excellent thermal stability compared to reference Rh‐OH:PC71BM device. The success of our monomolecular strategy can provide a new way to develop high‐performance SCOSCs. 相似文献
A new broad bandgap and 2D‐conjugated D‐A copolymer, PBDTBTz‐T , based on bithienyl‐benzodithiophene donor unit and bithiazole (BTz) acceptor unit, is designed and synthesized for the application as donor material in polymer solar cells (PSCs). The polymer possesses highly coplanar and crystalline structure with a higher hole mobility and lower HOMO energy level which is beneficial to achieve higher open circuit voltage (Voc) of the PSCs with the polymer as donor. The PSCs based on PBDTBTz‐T :PC71BM blend film with a lower PC71BM content of 40% demonstrate a power conversion efficiency (PCE) of 6.09% with a relatively higher Voc of 0.92 V. These results indicate that the lower HOMO energy level of the BTz‐based D–A copolymer is beneficial to a high Voc of the PSCs. The polymer, with highly coplanar and crystalline structure, can effectively reduce the content of fullerene acceptor in the active layer and can enhance the absorption and PCE of the PSCs.
6,7-Dialkoxy-2,3-diphenylquinoxaline based narrow band gap conjugated polymers, poly[2,7-(9-octyl-9H-carbazole)-alt-5,5-(5,8-di-2-thinenyl-(6,7-dialkoxy-2,3-diphenylquinoxaline))] (PCDTQ) and poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(5,8-di-2-thinenyl-(6,7-dialkoxy-2,3-diphenylquinoxaline))] (PFDTQ), have been synthesized by Suzuki polycondensation. Their optical, electrochemical, transport and photovoltaic properties have been investigated in detail. Hole mobilities of PCDTQ and PFDTQ films spin coated from 1,2-dichlorobenzene (DCB) solutions are 1.0 × 10-4 and 4.1 × 10-4 cm2V-1s-1, respectively. Polymer solar cells were fabricated with the as-synthesized polymers as the donor and PC61BM and PC71BM as the acceptor. Devices based on PCDTQ:PC71BM (1:3) and PFDTQ:PC71BM (1:3) fabricated from DCB solutions demonstrated a power conversion efficiency (PCE) of 2.5% with a Voc of 0.95 V and a PCE of 2.5% with a Voc of 0.98 V, respectively, indicating they are promising donor materials. 相似文献
The synthesis, characterization, and photophysical and photovoltaic properties of two anthracene‐containing wide‐band‐gap donor and acceptor (D–A) alternating conjugated polymers ( P1 and P2 ) are described. These two polymers absorb in the range of 300–600 nm with a band gap of about 2.12 eV. Polymer solar cells with P1 :PC71BM as the active layer demonstrate a power conversion efficiency (PCE) of 2.23% with a high Voc of 0.96 V, a Jsc of 4.4 mA cm−2, and a comparable fill factor (FF) of 0.53 under simulated solar illumination of AM 1.5 G (100 mW cm−2). In addition, P2 :PC71BM blend‐based solar cells exhibit a PCE of 1.42% with a comparable Voc of 0.89 V, a Jsc of 3.0 mA cm−2, and an FF of 0.53.
Two conjugated molecules, TADPP3 and TADPP2‐TT , are reported, in which three and two dithienyldiketopyrrolopyrrole (DPP) moieties, respectively, are substituted at the meta positions of benzene. Based on cyclic voltammetry and absorption data, TADPP3 and TADPP2‐TT possess similar HOMO and LUMO energies of about ?5.2 and ?3.4 eV, respectively. Thin films of TADPP3 and TADPP2‐TT exhibit p‐type semiconducting behavior with hole mobilities of 2.36×10?3 and 3.76×10?4 cm2 V?1 s?1 after thermal annealing. Molecules TADPP3 and TADPP2‐TT were utilized as p‐type photovoltaic materials to fabricate organic solar cells after blending with phenyl C71 butyric acid methyl ester ( PC71BM ) and phenyl C61 butyric acid methyl ester ( PC61BM ). The relatively low JSC and fill factor values can be attributed to poor film morphologies based on AFM and XRD studies. A solar cell with a thin film of TADPP3 with PC71BM in a weight ratio of 1:2 exhibits a high open‐circuit voltage (VOC) of 0.99 V and a power conversion efficiency (PCE) of 2.47 %. Interestingly, TADPP3 can also be employed as an n‐type photovoltaic material. The blended thin film of TADPP3 with P3HT in a weight ratio of 1:2 gave a high VOC of 1.11 V and a PCE of 1.08 % after thermal annealing. 相似文献
High‐molecular‐weight conjugated polymer HD‐PDFC‐DTBT with N‐(2‐hexyldecyl)‐3,6‐difluorocarbazole as the donor unit, 5,6‐bis(octyloxy)benzothiadiazole as the acceptor unit, and thiophene as the spacer is synthesized by Suzuki polycondensation. HD‐PDFC‐DTBT shows a large bandgap of 1.96 eV and a high hole mobility of 0.16 cm2 V−1 s−1. HD‐PDFC‐DTBT:PC71BM‐based inverted polymer solar cells (PSCs) give a power conversion efficiency (PCE) of 7.39% with a Voc of 0.93 V, a Jsc of 14.11 mA cm−2, and an FF of 0.56.
Designing and synthesizing high‐performable electron donor materials are very important for fabricating organic solar cell devices with high power conversion efficiency (PCE). In this work, quantum chemical and molecular dynamics calculations coupled with the Marcus‐Hush charge transfer model were used to investigate the photovoltaic properties of 4Cl‐BPPQ/PC61BM. Results reveal that 4Cl‐BPPQ/PC61BM system theoretically possesses a large open‐circuit voltage (1.29 V), high fill factor (0.90), and over 9% PCE. Moreover, calculations also reveal that the 4Cl‐BPPQ/PC61BM system has a middle‐sized exciton binding energy (0.492 eV), but relatively small charge‐dissociation and charge‐recombination reorganization energies (0.345 eV and 0.355 eV). Based on the 4Cl‐BPPQ/PC61BM complex, the charge‐dissociation rate constant, kdis, is estimated to be as large as 6.575×1012 s?1, while the charge‐recombination one, krec, is very small (<1.0 s?1) under the same condition due to the very small driving force (ΔGrec=?1.900 eV). In addition, by means of an amorphous cell containing one hundred 4Cl‐BPPQ molecules, the hole carrier mobility of 4Cl‐BPPQ solid is estimated as high as 3.191×10?3 cm2·V?1·s?1. In brief, our calculation shows that 4Cl‐BPPQ/PC61BM system is a very promising organic solar cell system, and is worth of making further device research by experiments. 相似文献