| 초록 |
Two small molecules, composed of NDT donor core and TPD acceptor group, end-capped with and without an alkyl-bithiophene, defined as NDT(TPD)2 and NDT(TPDTT)2 were designed and synthesized. The thermal and electrochemical analyses were carried out for both the small molecules, revealed good thermal stability along with high decomposition temperature (>350°C). NDT(TPD)2 showed a deep HOMO (-5.38 eV), than HOMO (-5.26 eV) of NDT(TPDTT)2. While X-ray diffractometry suggests crystalline and amorphous nature of NDT(TPD)2 and NDT(TPDTT)2 respectively, the space charge limited current analysis revealed high hole mobility in NDT(TPD)2 and appreciable charge balance in NDT(TPDTT)2. The organic solar cell (OSC) devices fabricated using NDT(TPD)2 and NDT(TPDTT)2 as donor show power conversion efficiency (PCE) of 0.26% and 0.8% respectively. While NDT(TPDTT)2 device after blending with additive, yielded maximum PCE of 1.31% resulting from enhanced Jsc 3.32 mA/cm2, Voc 0.75 V and FF of 52.44. |
