| Organic photodetectors(OPDs)have attracted continuous attention due to their outstanding advantages,such as tunability of detection wavelength,low-cost manufacturing,light weight,compatibility with flexible devices,as well as ease of processing,which have become a new member of the photodetector family.As for the application field,the new type OPDs have shown great application prospects in portable and wearable devices,complementing traditional inorganic photodetectors.With the continuous deepening of research,some of the performance indicators of OPDs have approached or even surpassed traditional inorganic photodetectors,but the response speed in the order of microseconds still hinders the marketization of OPDs.This also makes it difficult for OPDs to integrate a variety of excellent performance indicators into one device,which is also a stumbling block for the further development of OPDs.In view of the problems existing in the field of OPDs,this paper studies OPDs from the two dimensions of device structure and manufacturing process.We proposed an OPD based on tandem structure,and conducted an in-depth analysis of the mechanism of tandem OPDs.In this work,the tandem OPDs integrate excellent performance such as fast response,low noise current and broadband.The performance of tandem OPDs is at a relatively advanced level.By adjusting the thickness of the active layers to simultaneously reduce the carrier transit time and resistance-capacitance(RC)time constant of the device,a fast response speed of 146.8ns has been achieved.To the best of our knowledge,the response speed of this new type OPDs is faster than that of previously reported OPDs until now.Moreover,the multi-level barrier enhancement structure of the tandem device brings a low noise current of7.82×10-14 A Hz-1/2.In addition,the tandem OPDs have been successfully integrated into the optical communication system as signal receivers,proving the accurate transmission of digital signals from visible to near-infrared optical communication.We believe that the tandem OPDs have broad application potential in wireless transmission systems,and have certain guiding significance for the production of new high-performance photodetectors.In order to solve the problem of the difficult and complex preparation process of the tandem structure,we ameliorated the preparation technology,which directly superposed the two active layers by the solution method to prepare OPDs based on the semi-tandem structure.The active layers with complementary absorption spectrum effectively enhance the light absorption in the range of 300-1000 nm,making the semi-tandem OPD achieve a high responsivity of 0.48 A W-1 at 830nm,which is close to the highest responsivity in the near-infrared region reported so far.In addition,benefitting from the mode of blocked electron transport induced by the semi-tandem structure,the semi-tandem OPD obtained a low dark current density of 2.04×10-8 A cm-2.The device showed a significant performance improvement,indicating that this new process method and device structure have a huge practical application value.This paper systematically introduces the basic content of OPDs with performance parameters,device structure,working principle,etc.and studies the performance of OPDs from the two dimensions of innovative device structure and innovative manufacturing process.The performance of the OPDs based on the tandem or semi-tandem structure have been significantly improved,and the mechanism of the tandem device was analyzed in depth for the first time.The content described in the article is a bold innovation in the OPD field and provides new ideas for future research of the OPDs. |
PDF Full Text Request