Solution-processable Organic Semiconducting Materials for Photovoltaic Applications
Author | : Jianguo Mei |
Publisher | : |
Total Pages | : |
Release | : 2010 |
ISBN-10 | : OCLC:769020256 |
ISBN-13 | : |
Rating | : 4/5 (56 Downloads) |
Book excerpt: Using diketopyrrolopyrrole (DPP) as an electron acceptor, amphiphilic discrete oligomers that can self-assemble into highly ordered nanostructures for organic field-effect transistors (OFETs) and molecular bulk-heterojunction solar cells (OPVs) were studied. Charge mobility as high as 4 x 10-3 cm2V-1s-1 was obtained from OFET measurement and PCEs of 0.7% were reported with a high fill factor of 0.58 in molecular BHJ solar cells with PCBM as an electron acceptor. A DPP-based thermocleavable polymer was also prepared and OPVs based on this polymer demonstrated an enhanced PCE of 1.44% upon cleavage. In chapter 6, isoindigo was introduced as an electron acceptor in [pi]-conjugated materials. Isoindigo-based oligothiophenes were prepared and used as donor materials in molecular bulkheterojunction OPVs and power conversion efficiencies up to 1.85% were achieved. Three isoindigo-based polymers were synthesized to validate the hypodissertation that charge mobility in conjugated polymers can be enhanced via enforcement of [pi]-[pi] interactions by means of introducing biphasic solubilizing groups. The results from SCLC modeling of J-V characteristics of single-carrier diodes are consistent with the hypodissertation presented where a nearly 10-fold increase in hole mobilities was observed for polymers with biphasic solubilizing group. In addition, a facile approach to isoindigo-based n-type conjugated polymers was also reported, in which the LUMO level as deep as -4.1 eV and deep HOMOs of ~6.0 eV were found. These polymers can be considered as an alternative to commonly used acceptors such as PCBM derivatives currently employed in polymer-based solar cell devices.