Identification and Mitigation of Transient Phenomena That Complicate the Characterization of Halide Perovskite Photodetectors

Abstract

Halide perovskites have shown promise to advance the field of light detection in next-generation photodetectors, offering performance and functionality beyond what is currently possible with traditional inorganic semiconductors. Despite a relatively high density of defects in perovskite thin films, long carrier diffusion lengths and lifetimes suggest that many defects are benign. However, perovskite photodetectors show detection behavior that varies with time, creating inconsistent device performance and difficulties in accurate characterization. Here, we link the changing behavior to mobile defects that migrate through perovskites, leading to detector currents that drift on the time scale of seconds. These effects not only complicate reproducible device performance but also introduce characterization challenges. We demonstrate that such transient phenomena generate measurement artifacts that mean the value of specific detectivity measured can vary by up to 2 orders of magnitude even in the same device. The presence of defects can lead to photoconductive gain in photodetectors, and we show batch-to-batch processing variations in perovskite devices gives varying degrees of charge carrier injection and photocurrent amplification under low light intensities. We utilize the passivating effect of aging to reduce the impact of defects, minimizing current drifts and eliminating the gain. This work highlights the potential issues arising from mobile defects, which lead to inconsistent photodetector operation, and identifies the potential for defects to tune photodetection behavior in perovskite photodetectors.

Modulating Dimensionality of 2D Perovskite Layers for Efficient and Stable 2D/3D Perovskite Photodetectors

“…The LDR of 2D/3D perovskite devices increased particularly in the weak light intensity range. The trap-assisted nonradiative losses can reduce the charge carrier collection efficiency, leading to undesired nonlinear responses at low light powers. , As the light power increases, the trap states are filled, resulting in a saturation operation. Therefore, we attributed the enhanced weak light detection capability of the IPA-BAI PD to the significant reduction of trap states after mixed-phase 2D perovskite modification.…”

Transient On/Off Photocurrent Response of Halide Perovskite Photodetectors

“…Recent works on PDs explain the origin of the initial peak well in terms of capacitive effects. These photocharging features can be due, for example, to the separation of electron and hole distributions in organic semiconductors. ,− It is well-known that the capacitance in halide perovskite measured by impedance spectroscopy is a strong function of incident light and shows very large values. − As mentioned before, in perovskite PDs, it has been observed that the large capacitance has a predominant effect. , For simplicity, we describe the capacitive effect with a simple constant capacitor C m that represents the low-frequency capacitance of the device. The transient dependence of the capacitance on light is ignored in the first approximation.…”

“…Ideally, a fully flat current response is required, but measurements made over many years with silicon, organic, and perovskite PDs show a number of distinct characteristics. , In addition, the detection behavior of perovskite PDs exhibits temporal variations and current drift. These features often result in significant challenges in the characterization of device performance. − …”

“…In Figure C, another pattern is shown where the current increases slowly from the first instant. , These responses have been recognized from early measurements of perovskite PDs , and attributed to the large capacitance present in the devices. These problems of the slow rise of the photocurrent persist in current perovskite PDs. ,, The different types of features, peak, fast–slow rise, and slow rise, have been amply reported in different types of PDs. ,,,,− …”

Mn(II)-Activated Zero-Dimensional Zinc(II)-Based Metal Halide Hybrids with Near-Unity Photoluminescence Quantum Yield

“…Lead-based metal halide perovskites with the general structural formula ABX 3 have received widespread attention from the scientific community in recent years due to their excellent optoelectronic properties, and they have been used in solar cells, light-emitting diodes, photodetectors and other fields [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Although remarkable achievements have been made in the field of optoelectronic applications, the inherent toxicity and instability of lead-based materials limit their further practical applications [15,16].…”