寬波長感測範圍之雙摻雜光增益有機光偵測器

Abstract

本論文摻雜兩種不同吸收波段之近紅外光染料於有機二極體元件中，增加元件近紅外光波段至1200nm的吸收，同時有效利用光電流增益效應提升元件光響應率。當持續操作元件於逆向偏壓下時，有機材料層吸收光子後產生激子，之後分離成電子電洞對，其中電洞會經由P3HT分子傳遞至外部電路，電子則會因近紅外光染料在能階上形成的陷阱所捕獲，當不斷地累積電子後產生的空間電荷會誘發一電場吸引外部電路的電洞注入元件，使得外部量子效率大於100%，一般稱為光電流增益效應。此效應可明顯提升元件之光偵測度，同時因為摻雜了兩種不同吸收波段之近紅外光染料，使得元件偵測波段自可見光大幅延長至近紅外光波段。

In this study, through doping of two different near-infrared (NIR) materials in organic photodiodes, the absorption of the device was extended to 1200 nm. Meanwhile, it effectively promoted the responsivity of the device by the process of photomultiplication. This mechanism could be attributed to trapping of electrons, originating from the photogenerated electron/hole pairs, at the NIR dyes. The trapped carriers could induce an electric field and decrease the injection barrier, eventually leading to the injection of holes from the external circuits and high photocurrent multiplication phenomenon occurred at reverse bias conditions. Because codoping of two different NIR dyes , we have successfully fabricated highly sensitive polymer photodetectors exhibiting broad spectral responses ranging from the ultraviolet to the NIR region.