Palraj RanganathanKuang-Hao ChengWei-Ling ChenCheng-Wei CaiWei-Liang LinWei ChenJyh-Chien ChenLEE-YIH WANG2024-07-172024-07-172024-07-01https://www.scopus.com/record/display.uri?eid=2-s2.0-85196494828&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/719870Metal-free organic semiconductors have emerged as a kind of promising star material in photocatalysis. However, their photocatalytic efficacy is impeded by the great recombination rate of the photogenerated charge carriers. Herein, we demonstrate the devising of solution-processable organic semiconductor bulk heterojunction (BHJ) systems with varying ratios by using BP3DT and PC61BM as the donor (D) and acceptor (A) candidates, respectively, for enhanced selective CO production from CO2 photoreduction. The prepared BP3DT/PC61BM BHJs are solution-processed on both glass substrates (GS) and molecular sieves (MS) via a drop-casting technique to form an active thin film and porous photocatalysts to catalyze CO production. All BP3DT/PC61BM BHJs efficiently produce CO as the primary product in the existence of trace-level TEA/H2O (0.5 mL). Our results show that the photocatalytic efficiency depended on the D/A w% ratios and its nanoscale phase separation morphology within the BHJ, contributing to the promotion of exciton dissociation. The BHJ undergoes an ostensible morphological transition from large-scale phase-separation to a fine mixed homogeneous nanoscale by varying the BP3DT/PC61BM blend ratio from 30/70 w% to 70/30 w%, which increases the interfacial area and shortens the distance of the exciton to the D/A surface, and promotes charge carrier separation, corroborated by photo-optical and photoelectrochemical experimental results. Accordingly, the resulting BP3DT/PC61BM BHJ@MS with a D/A ratio of 70/30 w% achieves a CO yield of 819 μmol·gcat-1 h-1, surpassing those of pure PC61BM (126 μmol·gcat-1 h-1) and BP3DT (72 μmol·gcat-1 h-1) by 6.5- to 11.3-fold and also exceeding that of metal-free linear conjugated polymer-based organocatalysts reported to date. Specifically, this is the first work to develop an organic-semiconductor-based BHJ photocatalyst, which may offer a nascent way to design more efficient organocatalysts for CO2 reduction.falseCO2 conversionexciton dissociationnanoscale phase morphologyorganic bulk heterojunctionphotocatalysis[SDGs]SDG13journal article10.1021/acssuschemeng.4c014892-s2.0-85196494828