Morphology Evolution Strategy for Efficient Energy Harvesting and Light Signal Detection in Organic Electronic Devices

Organic semiconductor based solution processable optoelectronic devices have attracted much attention owing to their advantages such as molecular tailoring, cost-effectiveness, great absorption coefficient, light weight, flexibility, and so on. By developing of the organic semiconductors like conjugated polymer donor and non-fullerene acceptors (NFAs), organic photovoltaics (OPVs) beyond the power conversion efficiency (PCE) of 19% and organic photodetectors (OPDs) have achieved the detectivity greater than 10¹⁴ Jones. These desirable results are originated from the morphology control strategies by using various strategies. Despite the blended system of polymer donor (PM6) and NFA (BTP-4F-12), the molecular orientation may be randomly located due to the difference in surface energy and density of the materials during spin coating. In this study, we suggest the morphology evolution strategy in terms of thin-film lamination process. We controlled morphology of photoactive layer by our newly designed thin-film coating process names transfer-lamination. 1) Our newly developed process can control the molecular orientation as intended by morphology turn over process and it can induce the well-distributed donor/acceptor phase. Moreover, our transfer lamination process can be applied to any solution-processable materials regardless of the thickness of thin films. Therefore, the OPVs and OPDs prepared by transfer-lamination showed PCE approaching the 16% and detectivity of 3.61×10¹³ Jones, respectively. 2) Ternary system is the promising morpohlogy evolution strategy by incorporating the high LUMO level guest NFA (EH-IDTBR) into the PM6:BTP-4F-12 blend inducing the effiicient abroption ability and charge dynamics (charge transfer and blocking). Also, when applying the ternary strategy, it is important to control the ratios among the materials with consideration of energy levels, miscbilities. Accordingly, the optimal ternary OPVs and OPDs composed of PM6:EH-IDTBR:BTP-4F-12 (1:0.1:1.1, wt/wt/wt) revealed the improved performances such as PCE of 16.20 % and detectivity of 1.33 × 10¹³ Jones, respectively. 3) Moreover, the ternary system can be applied to the dry-transfer lamination process. This is one-step advanced strategy by fusing the process and material design and it can lead to further improvement by synergy effects through the integration of both advantages. Consequently, transfer-laminated optimal ternary condition achieved the PCE of over 17% in the OPVs and 4.21×10¹³ Jones from the OPDs.