Solution-processed near-infrared Cu(In,Ga)(S,Se)2 photodetectors with enhanced chalcopyrite crystallization and bandgap grading structure via potassium incorporation

Abstract

Although solution-processed Cu(In,Ga)(S,Se)2 (CIGS) absorber layers can potentially enable the low-cost and large-area production of highly stable electronic devices, they have rarely been applied in photodetector applications. In this work, we present a near-infrared photodetector functioning at 980 nm based on solution-processed CIGS with a potassium-induced bandgap grading structure and chalcopyrite grain growth. The incorporation of potassium in the CIGS film promotes Se uptake in the bulk of the film during the chalcogenization process, resulting in a bandgap grading structure with a wide space charge region that allows improved light absorption in the near-infrared region and charge carrier separation. Also, increasing the Se penetration in the potassium-incorporated CIGS film leads to the enhancement of chalcopyrite crystalline grain growth, increasing charge carrier mobility. Under the reverse bias condition, associated with hole tunneling from the ZnO interlayer, the increasing carrier mobility of potassium-incorporated CIGS photodetector improved photosensitivity and particularly external quantum efficiency more than 100% at low light intensity. The responsivity and detectivity of the potassium-incorporated CIGS photodetector reach 1.87 A W−1 and 6.45 $$\times$$ × 1010 Jones, respectively, and the − 3 dB bandwidth of the device extends to 10.5 kHz under 980 nm near-infrared light.

Role of Heterocyclic Organic Compounds on the Optoelectronic Properties of Halide Perovskite Single Crystals

“…According to the low light power, I = AP θ , where I, A, P, and θ represent the photocurrent, the constant depending on the wavelength, the light power intensity, and the exponent determining the response to light intensity, respectively. 31 The control and modified crystals showed θ values of 0.87 and 0.93, respectively. The different values of θ suggest different charge collection efficiencies of both the crystals.…”

“…Figure S2b shows the comparison of photocurrents of both the crystals as a function of illumination intensity. According to the low light power, I = AP θ , where I , A , P , and θ represent the photocurrent, the constant depending on the wavelength, the light power intensity, and the exponent determining the response to light intensity, respectively …”

Surface plasmon resonance effects of Ag@ZnO core–shell nanostructure in UV and visible light for photodiode applications

“…The voltage‐dependence of the photocurrent is weaker at low light intensities than at high light intensities, but toward high light intensities, the photocurrent is more pronounced than at low intensities. This can be explained by the fact that with increasing light intensity, more photons are absorbed, resulting in more photogenerated carriers, a decrease in recombination current, 62 and an increment in external quantum efficiency (EQE) 63 . The ratio of photocurrent to dark current is called the on/off ratio of the photodiode and provides information about the light response level of the optical device.…”

Environment-friendly copper-based chalcogenide thin film solar cells: status and perspectives

“…4 Cu Ch materials have been used for many optoelectronic device applications, such as photodetectors, light-emitting diodes (LEDs), near-infrared plasmon resonances, biomedical imaging, and biosensors, that can operate in a wide wavelength range from visible to the near-infrared (NIR) due to tuneable bandgaps. 11–15 In addition, for solar cell application, Cu Ch materials can be used as photoactive or charge selecting contact materials. 16,17 Specifically, their application as photoactive materials in solar cell device is more dominant due to their high hole mobility (up to 200 cm 2 V −1 s −1 ), tunable bandgap (from around 1.0 to 2 eV), high absorption coefficient (up to 10 5 cm −1 ), chemical stability, etc.…”