Poly(aryleneethynylene)s(PAEs) can be used in polymer light-emitting devices (PLED) and photovoltaic cells due to their relatively high efficient energy transfer and luminescence. The emission color of PAEs can be turned by incorporating narrow band-gap comonomers into the PAEs' backbone. A new class of poly(aryleneethynylene)s containing an aryl heterocyclic structure was prepared by Pd-catalyzed cross couplings between 4

7-dibromo-2

1

3-benzothiadiazole(BT)and 2

7-diet-hynylene-9

9-dioctylfluorene(PFE)with different feed radio of PFE to BT

using Pd(PPh

3

)

4

and CuI as catalysts in the presence of triethylamine and toluene. In the case of Pd-catalyzed cross couplings

each individual narrow-band-gap unit is separated from both sides by wide-band-gap segments when the narrow-band-gap component is under or equal to 50% in the copolymer. The narrow-band-gap units function as exciton traps allow efficient intramolecular energy transfer from wide-band-gap segments to narrow-band-gap unit. All these polymers had a number-average (molecular) mass

M

n

about 4 000

1

2 000 and showed good solubility in chloroform and toluene. The actual molar ratios of PFE to BT in the copolymers were estimated by means of elemental analysis. The results indicate that the actual ratio of PEF to BT in the copolymer is very close to the feed ratio. The absorption and photoluminescent spectra of the copolymers were studied. The maximal emissions of PL and UV spectra slightly red-shifted with gradual increase of BT's content. The result indicates that when the polymer contains alternating narrow band-gap aromatic units BT and large band-gap units PFE the tendency is to form a π-stacked structure which will be enhanced due to intermolecular charge transfer (CT) between polymer molecules. So that we could tune the emission color of polymers through attaching different ratio of narrow band-gap comonomer.