Photoresponsivity and photodetectivity properties of copper complex-based photodiode

A Au/CuNiCoS4/p-Si photodiode: electrical and morphological characterization

In this present work, CuNiCoS₄ thiospinel nanocrystals were synthesized by hot injection and characterized by X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive X-ray spectroscopy (EDS). The XRD, EDS, and HR-TEM analyses confirmed the successful synthesis of CuNiCoS₄. The obtained CuNiCoS₄ thiospinel nanocrystals were tested for photodiode and capacitance applications as interfacial layer between Au and p-type Si by measuring I-V and C-V characteristics. The fabricated Au/CuNiCoS₄/p-Si device exhibited good rectifying properties, high photoresponse activity, low series resistance, and high shunt resistance. The C-V characteristics revealed that capacitance and conductance of the photodiode are voltage-and frequency-dependent. The fabricated device with CuNiCoS₄ thiospinel nanocrystals can be employed in high-efficiency optoelectronic applications.

Defect suppression and photoresponsivity enhancement in methylammonium lead halide perovskites by CdSe/ZnS quantum dots

Potential strategies such as surface passivation and perovskite material halide mixing may protect material surfaces, improve luminescence, and reduce charge traps for device stability. In this study, we used deep level transient spectroscopy to investigate the effect of CdSe/ZnS core-shell quantum dots (QDs) on defect states and carrier transport in methylammonium (MA) lead halide perovskites (CH₃NH₃PbX₃ where X  = I, Br). In MAPbI₃ and MAPbI₂Br films with CdSe/ZnS QDs, the density of hole traps located at E_v + 0.37 eV and E_v + 0.56 eV was reduced dramatically. Deep traps at E_v + 0.78 eV and E_v + 1.08 eV were removed, and one broad electron trap signal dominated. Film photoresponsivity under 600-nm wavelength light and a bias voltage of -0.7 V was 10 and 18 mA/W, which is 100 and 27 times larger than the 0.1 and 0.67 mA/W of bare perovskites (PS), respectively. This demonstrates that carrier transport was enhanced due to defect suppression. Our findings on defect suppression and photoresponsivity enhancement provide an important direction for optimizing high-performance PS device fabrication.