Wavelength-Dependent Charge Carrier Dynamics for Single Pixel Color Sensing Using Graded Perovskite Structures

Abstract

We report smart color-sensing devices of two-dimensional lead halide perovskites that exhibit a graded band gap across the film. We observe that the device short-circuit photocurrent is strongly dependent on excitation wavelength λ, and this arises through photoabsorption at different depths in the sample due to the graded bandgaps present. This λ signature in the response of the device is observed in case of steady-state excitation when incident from the high bandgap side of the film, where a complete reversal in the polarity of the photocurrent I ph (t) is obtained as the excitation wavelength is spanned across the visible spectrum. The transient photocurrent reveals λspecific response arrived from a combination of positive and negative I ph (t) components. The uniqueness of I ph (t) as a function of incident λ can be utilized to examine spectral purity without dispersive optical elements. An equivalent circuit model description provides a possible glimpse into the physical sources involved in contributing to these features.

Ultrafast Carrier Dynamics of Amorphous Zinc Tin Oxide Graded Thin Films

“…A detailed understanding of the carrier dynamics in semiconductor is extremely useful for the development of future optoelectronic systems. Ultrafast optical spectroscopy is a versatile technique to investigate the dynamic process and the corresponding relaxation mechanism of semiconductors. − Despite some effects, however, the carrier dynamics of ZTO are rarely addressed. , Due to the limited experimental data, the intrinsic carrier recombination mechanism following photon absorption in ZTO remains elusive and needs full discernment.…”

Perovskite Color Detectors: Approaching the Efficiency Limit

“…A comparison of the sensor characteristics with other vertically stacked sensor exhibits a distinct better agreement with the CMF than other structures in the literature studies. − ,,− Silicon SCSs suffer from the large overlap of the spectral responsivities due to the indirect band gap of crystalline silicon (c-Si). The idea of using stacked perovskite sensors has been proposed by Yakunin et al.…”

Vertically Stacked Perovskite Detectors for Color Sensing and Color Vision

“…Sensor concepts based on silicon, silicon alloys, organic materials, and perovskites have been proposed. [ 11–19 ] To ensure a correct measurement of the color information, the sensor signals for red, green, and blue must be linearly independent. Four‐terminal devices consist of three independent diodes, so that the sensor signals are inherently linearly independent.…”

“…Furthermore, a detailed analysis of the transient behavior of the photocurrent has been proposed to generate linearly independent color channels. [ 17,18 ] In this study, we focus on four‐terminal devices. Most four‐terminal color sensors are based on silicon and silicon alloys.…”