Abstract
Here we reported that a huge enhancement in photoluminescence (PL) efficiency of the conjugated polymer P3HT while the polymer was stretched by local deformation and dewetting in the optically inert polystyrene (PS) matrix. The PL enhancement increased exponentially with the local stress () that the enhancement reached ~40 times for ~ 120 MPa. The enhanced PL spectra showed substantial increases in the intrachain emission while the peak positions remained unaffected. The stress effect was about double of that in the amorphous MEH-PPV that, however, emitted light approximately two times more efficient than the crystalline P3HT when no stresses were applied. The stress effect was attributed to the induced molecular constraints that led to the reduced ability to accumulate local deformations (suppression of electron-phonon coupling) for charge trapping in the stretched P3HT chains. Furthermore, stretching the conjugated polymer did not alter the Raman absorption peaks although the Raman intensities increased substantially. We also investigated that the local stress of polymer in the dewetting process by the molecular chain flowed and constrained. The result might help in improving the performances of polymer-based devices.