基于电场调控的高性能紫外无机-有机复合结构光电探测器

通过溶液旋涂制备了结构为ITO/ZnO/P3HT∶ITIC/Ag的紫外无机-有机复合结构光电探测器,混合膜中聚合物给体（P3HT）和非富勒烯小分子受体（ITIC）的质量比为100∶1。由于载流子传输通道不连续,器件在零偏压下的暗电流密度很小,为5.8×10^-10 A·cm^-2,为器件实现外加电场可调和光电流倍增提供了条件。在正向偏压作用下,氧化锌（ZnO）界面层能吸收紫外光产生自由电子和空穴参与载流子输运（减少载流子复合几率）,从而提升器件的外量子效率（EQE）。随正向偏压的增加,ZnO界面层能够与活性层（P3HT∶ITIC）共同作用使器件的光电流倍增。45 V偏压下,器件在350 nm处可获得最小半高宽约为49 nm的EQE光谱响应峰,最高EQE、响应度和探测灵敏度分别为420000%、1 185 A·W^-1和1.8×10¹³ Jones。上述结果为制备基于电场调控的高性能紫外窄带无机-有机复合结构光电探测器提供了有效策略。

High-performance Ultraviolet Inorganic-organic Composite Structure Photodetectors Based on Electric Field Control

The ultraviolet inorganic-organic composite structure photodetectors with an architecture of ITO/ZnO/P3HT∶ITIC/Ag were fabricated by a solution spin-coating method.In the blended film,the weight ratio of polymer donor(P3HT)to non-fullerene small molecule acceptor(ITIC)is 100∶1.Due to the discontinuity of carrier transport-channel,the dark current density of devices under zero bias voltage is very small(5.8×10^-10 A·cm^-2),which provides the condition for devices to realize the external electric-field adjustable and photocurrent multiplied.Under forward bias voltages,the free electrons and holes generated by the zinc oxide(ZnO)interfacial layer through absorbing ultraviolet light can participate in carrier transport(reducing the probability of carrier recombination),thereby improving the external quantum efficiency(EQE)of devices.With the increase of forward bias voltages,ZnO interfacial layer can work together with active layer(P3HT∶ITIC)to multiply the photocurrent of devices.Under 45 V bias,the EQE spectral response-peak with a minimum half height width of about 49 nm can be obtained by devices at 350 nm,with the highest EQE,responsivity and detectivity of 420000%,1185 A·W^-1 and 1.8×10¹³ Jones,respectively.The above content provides an effective strategy to fabricate high-performance ultraviolet narrowband inorganic-organic composite structure photodetectors based on electric-field adjustment.