Self‐powered bifunctional perovskite photodetectors with both broadband and narrowband photoresponse

Abstract

Photodetectors generally operate exclusively in either the broadband or narrowband. Developing bifunctional photodetectors that can detect photons in both broadband and narrowband would bring significant versatility to the optoelectronic platform. Nevertheless, the design of bifunctional integrated devices remains challenging due to the differentiated strategies with respect to device structure and material combination. Herein, we propose introducing polyvinylpyrrolidone to increase the viscosity of the perovskite precursor solution, which introduces abundant defects and cavities into the perovskite film while maintaining a relatively low film thickness. Then, we use methylamine gas to postprocess the middle area of the film to promote directional recrystallization and densification, thereby realizing narrowband and broadband dual‐function photodetection in a single device at zero bias. Both ends of the film exhibit a near‐infrared peak response at 780 nm with a narrow full‐width at half maximum of approximately 30 nm without an external bias. The middle broadband photodetector exhibits a high responsivity of 329 mA W−1 and EQE up to 52.46% at 780 nm. We make full use of narrow‐band wavelength selective detection and broadband full‐spectrum detection to achieve double encryption during signal transmission. This work represents an important step toward the realization of perovskite‐based multifunctional integrated devices.

Light‐Induced Bipolar Photoresponse with Amplified Photocurrents in an Electrolyte‐Assisted Bipolar p–n Junction

“…The resulted photocurrents are shown in Figure 5b with significant distinction of the four states and the photodetector can achieve stable photodetection from 10 Hz to 1 kHz under switching light illumination of 365 and 265 nm (Figure S19, Supporting Information), suggesting that the precise recognition of the mixed two‐wavelength lights by only using one photodetector can be applied in encrypted dual‐channel optical communications. [ 47–50 ]…”

“…The resulted photocurrents are shown in Figure 5b with significant distinction of the four states and the photodetector can achieve stable photodetection from 10 Hz to 1 kHz under switching light illumination of 365 and 265 nm (Figure S19, Supporting Information), suggesting that the precise recognition of the mixed two-wavelength lights by only using one photodetector can be applied in encrypted dualchannel optical communications. [47][48][49][50] Vividly, the image displaying the characters of "USTC" was selected to be an input image as a proof-of-concept demonstration (Figure 5c). First, the input image was segmented and converted into 256 pixels which were encoded into a 16 × 16 digital matrix based on the rule: if a pixel is filled more than half by the pattern, the pixel is encoded as "1;" otherwise, the code is "0".…”

Recent progress in construction methods and applications of perovskite photodetector arrays

“…Photodiodes can work at zero bias voltage due to the built-in electric field that separates the electronhole pairs generated by the perovskite under photoexcitation and transports them to the corresponding electrodes, resulting in selfpowered photodetection. [63][64][65][66] However, since the photocurrent of the photodiode exhibits a nonlinear characteristic with the light intensity under zero bias voltage, 67 it generally works under reverse bias voltage to promote charge collection, which is different from photovoltaic devices. 68,69 Compared to planar photodetectors, photodiodes have low dark currents and faster response speeds, benefiting from the carrier rejection mechanism and short carrier transmission distances, respectively.…”

Extensible Integrated System for Real‐Time Monitoring of Cardiovascular Physiological Signals and Limb Health

“…One effective solution is transferring printed or fabricated optoelectronic devices on flexible substrates and then constructing the corresponding mechanical protection structures, such as 3D interconnection package structures. [ 16 ] With this method, light‐emitting diodes (LEDs) and photodetectors can be applied to curved surfaces, such as finger joints and bellies. [ 17 ] Another means of solving this problem is using the soft properties of pliable materials to design flexible photoelectric devices to form a certain bending or stretching ability on irregular, curved surfaces.…”