Synthesis, optical and photoelectrical characterizations of the novel 10-chloro-6H,8H-dichromeno[2,3-b:3′,4′-e]pyridine-6,8-dione (CDPD) and its photodiode application

• New derivative of heteroannulated chromeno[2,3-b]pyridine is constructed as CDPD structure.
• Three direct allowed transitions were observed with band gaps of 1.17, 2.24 and 3.40 eV.
• Strong PL intensity indicates an enhancement of optical characteristics of CDPD.
• Heterojunctions of CDPD/p-Si show high rectification characteristics.
• Heterojunctions of CDPD/p-Si indicate high photosensitivity under light illumination.

Friedländer condensation of 2-amino-6-chlorochromone-3-carboxaldehyde (1) with 4-hydroxycoumarin (2) under basic conditions afforded 10-chloro-6H,8H-dichromeno[2,3-b:3′,4′-e]pyridine-6,8-dione (3) (CDPD). Structure of CDPD was deduced based on its correct elemental analysis and spectral data (IR, 1H NMR, 13C NMR and mass spectra). Crystalline structure by using X-ray diffraction confirms a polycrystalline nature of the powder and films with monoclinic system. A flower-like morphology was resolved for the high magnification images of scanning electron microscopy. Three direct optical band gaps were obtained and found to be 1.17, 2.24 and 3.40 eV, respectively. A sharp single peak of photoluminescence in the visible region was observed and centered at around 683 nm as well as another two peaks at 417 and 386 nm. Rectification characteristics of the device based CDPD indicates that the device behaves as a diode. A maximum value of photosensitivity of the device was obtained under effect of 60 mW/cm2 and bias voltage of 1.25 V. The phototransient characteristics of the device confirm that the device can be operated as a photodiode.

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