Interfacial Engineering with Aluminum Oxide toward an Improved Self‐Powered Narrowband Visible‐Light Photodetection in Lead Halide Perovskite CH₃NH₃PbBr₃/p‐Si Heterojunctions

Abstract

Semiconductor heterojunctions consisting of lead halide perovskite (LHP) and silicon materials are important candidates for the fabrication of self‐powered visible‐light photodetectors. However, the interface recombination caused by interface trap states greatly deteriorates the performance of self‐powered photodetection, but fortunately, it can be suppressed by interfacial engineering. In this work, self‐powered narrowband visible‐light photodetection is demonstrated in the LHP CH3NH3PbBr3/p‐Si heterojunctions. Notably, the self‐powered photodetection performance is greatly enhanced by introducing an atomic‐layer‐deposition‐grown amorphous Al2O3 thin interlayer. Electrical and optical properties measurements suggest that the Al2O3 thin interlayer effectively passivates (reduces) the heterojunction interface trap states. On this basis, the CH3NH3PbBr3/Al2O3/p‐Si heterojunctions exhibit a decreased dark current and increased photocurrent simultaneously compared to CH3NH3PbBr3/p‐Si heterojunctions. Finally, a responsivity as high as 0.39 A W−1 and detectivity as high as 8.45 × 1012 Jones under the bias voltage of 0 V are obtained, which are higher than most reported state‐of‐the‐art devices. The results reported in this work will provide valuable pathways for the fabrication of high‐performance self‐powered narrowband photodetectors based on LHP/Si heterojunctions.

Ion Migration in the All-Inorganic Perovskite CsPbBr3 and Its Impacts on Photodetection

“…In recent years, the ion migration behaviors have further been evidenced both by experimental and theoretical investigations. − It was shown that halide species (Cl, Br, and I) have the lowest migration barrier height and diffuse with the assistance of grain boundaries and vacancy-type defects. ,, This results in an obvious energy band bending at both ends of the LHP film and subsequently produces the typical I – V hysteresis. For the LHP-based MSM-structured PDs, the effects of ion migration on the photodetection performance have rarely been concerned so far, although great efforts have been made previously, but they mainly focused on improving the photodetection performance of as-fabricated PDs and developing multifunctional (such as flexible, self-powered, and narrow/broad-band detection) devices. − In our opinion, the effects of ion migration should be considered in the LHP-based MSM-structured PDs because a bias voltage is necessarily applied, especially for weak light detection. It is worth noting that the ion migration has been observed in the mixed halide CsPbX 3 -based light-emitting diodes recently …”

Improved Perovskite CH3NH3PbI3 Thin Films by ZIF‐67 Additive Assisted Co Ion Doping toward High‐Performance and Stable Photodetectors

“…However, the PL intensity increases abruptly if the trap states are completely filled. Therefore, the trap state density (n trap ) is proportional to the excitation power threshold of complete trap-filling (P th ) (i.e., n trap ∼ P th [38,39] ). The P th can be obtained by fitting the excitation power dependence of integrated PL spectra with two linear functions, as shown in Figure 2b.…”

Fast Response, High Spectral Rejection Ratio, Self-Filtered Ultranarrowband Photodetectors Based on Perovskite Single-Crystal Heterojunctions

“…Narrowband photodetectors are indispensable in machine vision, sensing imaging, and encrypted communication due to high-precision spectral resolution. , Generally, narrowband photodetectors can be realized by the following three strategies: Broadband detectors coupled with bandpass filters or optical microcavity structures. , Absorbing or amplifying specific wavelengths by using materials with narrowband absorption capability or through a plasmonic effect. − Regulating the annihilation and collection of photogenerated carriers by the charge collection narrowing (CCN) principle. , In the integration and simplicity of application systems, there are many limitations in strategies (1) and (2), while narrowband photodetectors based on the CCN principle stand out. Recently, CCN-type narrowband photodetectors without filters have been extensively researched in organic–inorganic hybrids, , perovskite thick films, , and two-dimensional/three-dimensional (2D/3D) perovskite single crystals, , and they have been successfully developed in visible, , near-infrared − and dual-band narrowband photodetectors. , …”

“…8,9 In the integration and simplicity of application systems, there are many limitations in strategies (1) and (2), while narrowband photodetectors based on the CCN principle stand out. Recently, CCN-type narrowband photodetectors without filters have been extensively researched in organic−inorganic hybrids, 10,11 perovskite thick films, 12,13 and two-dimensional/three-dimensional (2D/3D) perovskite single crystals, 14,15 and they have been successfully developed in visible, 16,17 near-infrared 18−20 and dual-band narrowband photodetectors. 21,22 Organic−inorganic halide perovskites have exhibited excellent optoelectronic properties in narrowband photodetectors (PNPDs) such as strong light absorption coefficients, short transit time caused by high carrier mobility, and long charge diffusion length.…”