Modification Of The Active Layer In P3HT Photodetector

Organic photodetectors have received extensive attention due to the advantages of low production cost,variety and structure,simple synthesis process,and easy preparation in large areas.Photodiode-type organic photodetectors have been favored by researchers because of their linear dynamic range,fast response,and high sensitivity.However,higher photocurrent density and lower dark current density are the key to improving the detector performance of organic photodetectors.At present,the methods for enhancing the device photocurrent mainly include developing new photosensitive materials to improve absorption of photons,improving the morphology of photo-functional layers to improve charge transport efficiency,introducing interface modification layers to improve charge collection efficiency at electrodes,and structural optimization.To decrease the dark current of the device,bilayer structure or buffer layer has been applied in device fabrication.This work is based on the modification of the active layer in the traditional bulk heterojunction,which improves the performance of the organic photodetector.The content mainly consists of two parts.Part one:By adding a small amount of the cationic surfactant cetanetrimethylammonium bromide(CTAB)into the conventional bulk heterojunction P3HT:PC60BM,the photocurrent is improved due to the enhanced absorption and the dark current drops because of the ITO modification.A low-voltage,high-performance organic photodiode photodetector with a structure of ITO/TiO2/P3HT:PC60BM:CTAB/Mo03/Ag is obtained.Under-0.5 V reverse bias,the device switching ratio can be up to 1.17×105,the ratio of detection is 3.3×1014 Jones,the linear dynamic range is up to 112.2 dB,and the response is 0.3 A/W.The speed is faster(35 ?s/155 ?s)because CTAB plays a role in improving the crystal morphology of the optical functional layer,thereby greatly improving the performance of the device.Part two:We synthesized a new type of organic-inorganic hybrid perovskite quasi-two-dimensional nanosheet(PEA)2MAPb2l7 by a simple antisolvent method.The reaction was carried out at room temperature.The dimension of the synthesized organic-inorganic hybrid perovskite nanosheet is adjustable at about 3 ?m.The absorption and photoluminescence spectra of the nanosheets are adjustable from visible to near-ultraviolet.Based on this,we prepared an organic photodetector of P3HT and(PEA)2MAPb2I7 nanosheet composite film.The device structure is ITO/TiO2/P3HT:(PEA)2MAPb2I7/Au,and the switching ratio of the device is 2.84×102,and the transient photocurrent response time is fast(20 ?s/34 ?s),under-1 V reverse bias.This experiment provides the preliminary result of preparing active layer by using perovskite instead of fullerene and P3HT.This work tried to improve the performances of the traditional bulk heterojunction organic photodetectors by the modifying the active layer.At the same time,the application of synthetic quasi-two-dimensional organic-inorganic hybrid perovskite nanosheets to photodetectors provides unlimited possibilities for the realization of non-fullerene polymer photodetector devices.