Ambade Swapnil B, Ambade Rohan B, Eom Seung Hun, Baek Myung-Jin, Bagde Sushil S, Mane Rajaram S, Lee Soo-Hyoung
School of Semiconductor and Chemical Engineering, Chonbuk National University, 664-14, 1-ga Deokjin-dong, Deokjin-gu, Jeonju, Jeonbuk 561-756, Republic of Korea.
Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 689-798, Republic of Korea.
Nanoscale. 2016 Mar 7;8(9):5024-36. doi: 10.1039/c5nr08849f.
In an unprecedented attempt, we present an interesting approach of coupling solution processed ZnO planar nanorods (NRs) by an organic small molecule (SM) with a strong electron withdrawing cyano moiety and the carboxylic group as binding sites by a facile co-functionalization approach. Direct functionalization by SMs (SM-ZnO NRs) leads to higher aggregation owing to the weaker solubility of SMs in solutions of ZnO NRs dispersed in chlorobenzene (CB). A prior addition of organic 2-(2-methoxyethoxy)acetic acid (MEA) over ZnO NRs not only inhibits aggregation of SMs over ZnO NRs, but also provides enough sites for the SM to strongly couple with the ZnO NRs to yield transparent SM-MEA-ZnO NRs hybrids that exhibited excellent capability as electron transporting layers (ETLs) in inverted organic solar cells (iOSCs) of P3HT:PC60BM bulk-heterojunction (BHJ) photoactive layers. A strongly coupled SM-MEA-ZnO NR hybrid reduces the series resistance by enhancing the interfacial area and tunes the energy level alignment at the interface between the (indium-doped tin oxide, ITO) cathode and BHJ photoactive layers. A significant enhancement in power conversion efficiency (PCE) was achieved for iOSCs comprising ETLs of SM-MEA-ZnO NRs (3.64%) advancing from 0.9% for pristine ZnO NRs, while the iOSCs of aggregated SM-ZnO NRs ETL exhibited a much lower PCE of 2.6%, thus demonstrating the potential of the co-functionalization approach. The superiority of the co-functionalized SM-MEA-ZnO NRs ETL is also evident from the highest PCE of 7.38% obtained for the iOSCs comprising BHJ of PTB7-Th:PC60BM compared with extremely poor 0.05% for non-functionalized ZnO NRs.
在一次史无前例的尝试中，我们展示了一种有趣的方法，即通过一种简便的共功能化方法，将溶液法制备的氧化锌平面纳米棒（NRs）与一种带有强吸电子氰基部分和羧基作为结合位点的有机小分子（SM）相结合。由于SM在分散于氯苯（CB）中的ZnO NRs溶液中的溶解度较低，通过SM直接功能化（SM-ZnO NRs）会导致更高的聚集。在ZnO NRs上预先添加有机2-(2-甲氧基乙氧基)乙酸（MEA），不仅能抑制SM在ZnO NRs上的聚集，还为SM提供了足够的位点，使其与ZnO NRs强烈耦合，从而产生透明的SM-MEA-ZnO NRs杂化物，该杂化物在P3HT:PC60BM体异质结（BHJ）光活性层的倒置有机太阳能电池（iOSCs）中表现出优异的电子传输层（ETL）能力。一种强耦合的SM-MEA-ZnO NR杂化物通过增加界面面积降低了串联电阻，并调整了（铟掺杂氧化锡，ITO）阴极与BHJ光活性层之间界面处的能级排列。对于包含SM-MEA-ZnO NRs ETL的iOSCs，功率转换效率（PCE）显著提高（3.64%），相比原始ZnO NRs的0.9%有了进步，而聚集的SM-ZnO NRs ETL的iOSCs的PCE则低得多，为2.6%，从而证明了共功能化方法的潜力。对于包含PTB7-Th:PC60BM BHJ的iOSCs，共功能化的SM-MEA-ZnO NRs ETL的优越性也很明显，其最高PCE为7.38%，相比未功能化的ZnO NRs的极低的0.05%。
