Photovoltaic Photodetectors Based On Organic Metal Complexes

Organic photodetectors (PDs) have been the subject of extensive research in the past decade due to several inherent advantages such as large-area detection, wide selection of materials and low-cost fabrication on flexible substrates.The visible-blind ultraviolet (VB-UV) PDs and photovoltaic diodes were demonstrated by using tris-(8- hydroxyquinoline) rare earth (REq) (RE = Y, La,Gd, Eu, or Lu)as the electron acceptor (A), 1,3,5-tris(3-methyl- phenyl-phenylamino) triphenyamine (m-MTDATA) as the donor (D). It is found that Gdq diode with 1:1 ratio of m-MTDATA:Gdq offers a maximum power conversion of 2.52% and photo-responsivity of 230 mA/W at -7.5 V bias under 365nm radiation. This result is markedly higher than inorganic counterparts and previous reported organic PD. Moreover, the spectral response does not cover visible region. So high responsivity of Gdq-PD was attributed to the presence of dominant dissociation of the geminate carrier pairs at D:A intermolecular contacts. The improvement is the results of the lowest exciplex- and bulk-emissions among the REq-PD diodes and in the various ratio of D:A blend, more detail mechanism was also discussed. Besides degradation tests of the Gdq-PD diode under UV and fluorescent lamp show that the UV detector can suffer from the application conditions.We have demonstrated an organic photodetector (PD) which can detect 808 nm radiation in near infrared (NIR) region. The photodiode has a hybrid planar-mixed heterojunction structure: ITO/CuPc (10 nm)/CuPc:F16CuPc (1:2, 30 nm)/F16CuPc (20 nm)/LiF (1 nm)/Al. Here, CuPc and F16CuPc denote copper–phthalocyanine and hexadecafluoro–copper–pht- halo-cyanine complexes, respectively. The photodiode behaves a response time of 80 ns and a bandwidth of 14 MHz, which are higher than those of recent reports. At the same time, the response waveband of the photodiode covers longer wavelength in NIR comparing to the PD reported. It is conjectured that the high detection performance is due to high electron-mobility of F16CuPc, the large band edge offset between D/A molecules as well reasonable design of the diode structure. The detail working mechanism is also augured.