Embedded organic hetero-junction and negative-differential-resistance photocurrent based on bias-assisted natural-drying of organic drops

作者：Xie Xian Ning^*; Wang Yuzhan; Gao Xingyu; Lee Kian Keat; Sow Chorng Haur; Loh Kian Ping; Wee Andrew Thye Shen

来源：Organic Electronics, 2010, 11(9): 1543-1548.

DOI：10.1016/j.orgel.2010.06.014

• Photo current negative differential resistance
• Organic hetero-junction
• Bias-assissted drop casting

This work reports a bias-assisted natural-drying method in film drop-casting for the formation of an interfacial layer inside the bulk organic film. The natural-drying facilitates phase segregation in the polymer blend, while the simultaneous substrate bias application induces host electronic states in the interfacial layer. Consequently, an embedded organic hetero-junction is formed between the interfacial layer and bulk film. The hetero-junction not only enhances the separation of photoexcited electron-hole (e(p) - h(p)) pairs, but also allows for the selective storage and extraction of photocarriers through the bias-induced host states. Unusual photocurrent with negative-differential-resistance (NDR) is thus obtained for the first time for organic optoelectronic devices. The typical peak-to-valley ratio of the NDR peak is >= 500, and the NDR behavior is stable for prolonged photocurrent measurements. The bias-assisted natural-drying method is simple and cost-effective, and can be used as a new approach to the design and control of organic interfaces.

• 出版日期2010-9