| 초록 |
Herein, we present two novel small donor molecules, BDTTID and BDT3TID. These contain a BDT core and different numbers of thiophene group. The greater number of thiophene spacers in BDT3TID compared with BDTTID not only enhanced the absorption coefficient but also broadened and red shifted its absorption spectrum. These may enable achieving a high power conversion efficiency (PCE). The highest PCE, 5.54%, was obtained from the optimized BDTTID-based device treated with thermal annealing. In contrast, the thermal annealing of BDT3TID-based devices was found to deteriorate the device performance. Moreover, the BDTTID-based device was shown to possess superior thermal stability upon thermal treatment at 100 °C for 40 h. The PCE of the BDTTID remained above 66% of its initial PCE, whereas the BDT3TID was dramatically reduced from 4.60% to 1.11%. These results show the importance of controlling the crystallinity when designing small molecules for efficient and stable OPV devices. |
