Concepedia

Ultralow dark current in near-infrared perovskite photodiodes by reducing charge injection and interfacial charge generation

Riccardo Ollearo, Junke Wang, Matthew Dyson, Christ H. L. Weijtens, Marco Fattori, Bas T. van Gorkom, Albert J. J. M. van Breemen, Stefan C. J. Meskers, René A. J. Janssen, Gerwin H. Gelinck

Nature Communications · 2021 · 154 citations · 52 references

DOI Full text

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TL;DR

Metal halide perovskite photodiodes offer high responsivity and broad spectral sensitivity, but achieving high detectivity requires reducing dark current and noise, typically via charge‑blocking layers whose interfacial energy offset controls the magnitude and activation energy of dark current. Analysis of temperature‑dependent dark current in lead‑tin perovskite photodiodes shows that electron‑blocking layers suppress injection but induce interfacial charge generation; increasing the interfacial energy offset yields a device with ultralow dark current (5 × 10⁻⁸ mA cm⁻²), noise (2 × 10⁻¹⁴ A Hz⁻¹ᐟ²), and 1050 nm sensitivity, establishing a new design principle for high detectivity.

Abstract

Metal halide perovskite photodiodes (PPDs) offer high responsivity and broad spectral sensitivity, making them attractive for low-cost visible and near-infrared sensing. A significant challenge in achieving high detectivity in PPDs is lowering the dark current density (JD) and noise current (in). This is commonly accomplished using charge-blocking layers to reduce charge injection. By analyzing the temperature dependence of JD for lead-tin based PPDs with different bandgaps and electron-blocking layers (EBL), we demonstrate that while EBLs eliminate electron injection, they facilitate undesired thermal charge generation at the EBL-perovskite interface. The interfacial energy offset between the EBL and the perovskite determines the magnitude and activation energy of JD. By increasing this offset we realized a PPD with ultralow JD and in of 5 × 10-8 mA cm-2 and 2 × 10-14 A Hz-1/2, respectively, and wavelength sensitivity up to 1050 nm, establishing a new design principle to maximize detectivity in perovskite photodiodes.