In situ purification to eliminate the influence of impurities in solution-processed organic crystals for transistor arrays

One of the major factors driving the fast growth of the semiconductor manufacturing industry is a steady decrease in production costs. For traditional semiconductors, most of the cost originates from infrastructure, equipment, and processing. In contrast with low-cost strategies involving organic semiconductors, the materials can easily become one of the greatest costs. Here, we demonstrate a simple and efficient fabrication process, which involves in situ purification via spin-coating from organic semiconductor/polymer blends, to eliminate the influence of impurities on the electrical properties of the semiconductor. Thus, we achieve the same performance using low-purity, low-cost materials for transistor arrays with patterned organic semiconducting crystals as that obtained from high-purity materials. The exclusion of impurities is attributed to the vertical phase separation and crystallization that occur during spin-coating, which produces purified organic semiconducting crystals. With this reduction in cost, our results can redirect organic electronics to seek the lowest purity and lowest cost material that still provides adequate performance, rather than simply using the highest purity and costliest materials.