Top‐Illuminated Organic Photodetectors beyond 1000 nm Wavelength Response Enabled by a Well‐Defined Interfacial Engineering

Abstract

OPD and readout integrated circuit (ROIC) enables several advantages. [6] For example, the sensor area can potentially reach a larger fill factor as the OPD is directly overlaid on top of an ROIC, which means that more incident photons will be absorbed by the photoactive layer (PAL), leading to imagers that are more sensitive to light. [5] In addition, the response spectra for organic semiconductors can be designed and tuned by adjusting the chemical structure, and the application of organic-based image sensors can be easily extended by changing the PAL materials with various light responses. [7,8] Among image sensors, near infrared (NIR) and shortwave infrared (SWIR) imaging technologies are essential to many applications, including health monitoring, [9,10] machine vision, [11] optical communication, [12] and spectro scopy. [13] Currently, the semiconductors utilized for the detection of NIR radiation are still determined by silicon (Si) technology, [14] such that the sensor structure requires high-temperature growth and complex bonding processes, and at a cost that remains prohibitive for large-area manufacturing. The external quantum efficiencies (EQEs) of Si-based detectors are also intrinsically limited when the incident light extends to the SWIR region, in which the wavelength (λ) is longer than 1000 nm.Considering various breakthroughs during the development of OPDs, it is noted that improvements that result in high performance always rely on both material innovation and stateof-the-art device engineering. An OPD with high EQEs of 66% and 67% at a wavelength of 940 and 1000 nm has been realized recently by using a specifically designed nonfullerene acceptor (NFA). [15] This result indicates the significant future potential of organic image sensor technology. For device engineering, photo multiplication type OPD has been developed successfully for highly sensitive sensors under weak light condition. Photomultiplication effect is commonly obtained by introducing charge traps in photoactive layer of OPD to realize interfacial trap-assisted charge injection, leading to the EQE larger than 100%, and the additional amplification systems are no longer needed due to its high EQE. [16,17] Also, OPD with narrowband spectral response has also been demonstrated by introducing the photomultiplication and charge injection narrowing Near infrared (NIR) and shortwave infrared (SWIR) image technologies are of interest for many emerging applications. Among photodetector technologies, organic photodetectors (OPDs) are groundbreaking light sensors with unique photon-to-electron responses at various wavelengths that offer limitless flexibility in field applications due to the tunable design of organic semiconductors. Herein, a top-illuminated OPD deposited on bottom aluminum electrode with a spectral response beyond a wavelength of 1000 nm is reported, which suggests a feasibility for image sensors integrated with bottom readout circuit. The results reveal that a device composed of aluminum-doped zinc oxide, nickel oxide, and...

Bulk-Heterojunction Adjustment Enables a Self-filtering Organic Photodetector with a Narrowband Response

“…11,42 A previous study has verified that the thiadizole (C�N�S) group of PD004 and the cyanid (−CN) group of PD-A2 are independently presented in the respective molecule (Figure S9). 43 Therefore, the C�N�S and C(−CN) 2 fragments are chosen as the characteristic peaks to identify the PD004 donor and PD-A2 acceptor, respectively, as also validated by the preliminary ToF-SIMS results shown in Figure S10. According to the ToF-SIMS 3D images shown in Figure 3, the 700 nm thick BHJ film possesses an interpenetrating PD004:PD-A2 network with a small domain size (Figure 3a), which is ideal for exciton dissociations and carrier transportations.…”

Double-Layered Strategy for Broadband Photomultiplication-Type Organic Photodetectors and Achieving Narrowband Response in Violet, Red, and Near-Infrared Light

“…The rising time ( t r ) and falling time ( t f ) of PM-OPDs are defined as the time interval for the photocurrent rising from 10% to 90% or falling from 90% to 10% of the saturated photocurrent, respectively. − At 803 nm light illumination, the t r or t f of PM-OPDs is approximately 7 or 12 ms at 5 V bias, respectively. The dynamic range (DR) of the PM-OPDs is described as that where the response characteristics can be kept constant under different light intensities, − which is commonly expressed as in which P lower and P upper represent the minimal and maximal incident light intensities, respectively. The J pi dependence on 803 nm incident light of the optimal PM-OPDs is displayed in Figure S7.…”

Organic Photodiode Integration on Si Substrates beyond 1000 nm Wavelength

“…The materials polymer donor and small-molecular acceptor were produced by Raynergy Tek Incorporation . The AZO and NiO nanoparticle dispersion was purchased from Avantama AG.…”

“…The materials polymer donor and small-molecular acceptor were produced by Raynergy Tek Incorporation. 48 The AZO and NiO nanoparticle dispersion was purchased from Avantama AG. The other chemicals and solvents used in this paper were purchased from the Sigma-Aldrich Chemical Corporation.…”