Large-scale commercial synthesis of bulk-heterojunction (BHJ) solar cell materials is very challenging and both time and energy consuming. Synthesis of π-conjugated polymers (CPs) with uniform batch-to-batch molecular weight and low dispersity is a key requirement for better reproducibility of high-efficiency polymer solar cells. Herein, a conjugated polymer (CP) PTB7-Th, well known for its high performance, has been synthesized with high molecular weight and low dispersity in a closed microwave reactor. The microwave reaction procedure is known to be more controlled and consumes less energy. The precursors were strategically reacted for different reaction time durations to obtain the optimum molecular weight. All different CPs were well characterized using 1H NMR, gel permeation chromatography (GPC), UV-vis, photoluminescence (PL), electron spin resonance (ESR), and Raman spectroscopy, whereas the film morphology was extensively studied via atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXRD) techniques. The effect of molecular weight on a conventional BHJ solar cell with PC71BM acceptor was investigated to derive systematic structure-property relationships. The CP obtained after 35 min of reaction time and integrated into BHJ devices under ambient conditions provided the best performance with a power conversion efficiency (PCE) of 8.09%, which was quite similar to the results of CPs synthesized via a thermal route. An enhanced PCE of 8.47% was obtained for the optimized polymer (35 min microwave reaction product) when device fabrication was carried out inside a glovebox. The organic thin-film transistor (OTFT) device with the microwave-synthesized CP displayed better hole mobility (0.137 cm2 V-1 s-1) as compared to that with the thermally synthesized CP. This study also proved that the device stability and reproducibility of the microwave-synthesized CP were much better and more consistent than those of the thermally developed CP.

中文翻译：

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高性能环境条件处理的聚合物太阳能电池和有机薄膜晶体管。

体-异质结（BHJ）太阳能电池材料的大规模商业合成是非常具有挑战性的，并且既耗时又耗能。批与批之间的分子量均一且分散度低的π共轭聚合物（CP）的合成是高效聚合物太阳能电池更好再现性的关键要求。在此，已经在封闭的微波反应器中以高分子量和低分散性合成了以其高性能而众所周知的共轭聚合物（CP）PTB7-Th。已知微波反应过程受到更多的控制并且消耗更少的能量。使前体策略性地反应不同的反应持续时间以获得最佳分子量。使用1H NMR，凝胶渗透色谱（GPC），UV-vis，光致发光（PL），电子自旋共振（ESR）和拉曼光谱，而薄膜形态则通过原子力显微镜（AFM）和掠入射X射线衍射（GIXRD）技术进行了广泛研究。研究了分子量对具有PC71BM受体的常规BHJ太阳能电池的影响，以得出系统的结构-性质关系。经过35分钟反应时间后获得的CP并在环境条件下集成到BHJ装置中，其性能最佳，功率转换效率（PCE）为8.09％，这与通过热途径合成的CP的结果非常相似。当在手套箱内进行设备制造时，对于优化的聚合物（35分钟的微波反应产物），PCE的提高值为8.47％。与热合成CP相比，具有微波合成CP的有机薄膜晶体管（OTFT）器件显示出更好的空穴迁移率（0.137 cm2 V-1 s-1）。这项研究还证明，微波合成CP的装置稳定性和可重复性比热显影CP更好，更一致。