Organic photodetectors (OPDs) have attracted continuous attention due to their outstanding advantages, such as tunability of detecting wavelength, low‐cost manufacturing, compatibility with ...lightweight and flexible devices, as well as ease of processing. Enormous efforts on performance improvement and application of OPDs have been devoted in the past decades. In this Review, recent advances in device architectures and operation mechanisms of phototransistor, photoconductor, and photodiode based OPDs are reviewed with a focus on the strategies aiming at performance improvement. The application of OPDs in spectrally selective detection, wearable devices, and integrated optoelectronics are also discussed. Furthermore, some future prospects on the research challenges and new opportunities of OPDs are covered.
Recent progress in organic photodetectors is reviewed, including different device structures, features, and operation mechanisms. Benefiting from the improved performance, the applications of organic photodetectors for selective detection, wearability, and integrated devices are highlighted.
Perovskite light‐emitting diodes (PeLEDs) show great application potential in high‐quality flat‐panel displays and solid‐state lighting due to their steadily improved efficiency, tunable colors, ...narrow emission peak, and easy solution‐processing capability. However, because of high optical confinement and nonradiative charge recombination during electron–photon conversion, the highest reported efficiency of PeLEDs remains far behind that of their conventional counterparts, such as inorganic LEDs, organic LEDs, and quantum‐dot LEDs. Here a facile route is demonstrated by adopting bioinspired moth‐eye nanostructures at the front electrode/perovskite interface to enhance the outcoupling efficiency of waveguided light in PeLEDs. As a result, the maximum external quantum efficiency and current efficiency of the modified cesium lead bromide (CsPbBr3) green‐emitting PeLEDs are improved to 20.3% and 61.9 cd A−1, while retaining spectral and angular independence. Further reducing light loss in the substrate mode using a half‐ball lens, efficiencies of 28.2% and 88.7 cd A−1 are achieved, which represent the highest values reported to date for PeLEDs. These results represent a substantial step toward achieving practical applications of PeLEDs.
Highly efficient perovskite light‐emitting diodes are achieved by implementing a simple and cost‐effective method for efficient outcoupling of waveguided light. A record external quantum efficiency of 28.2% is realized for the device based on cesium lead bromide (CsPbBr3), while retaining the same spectral response for broad viewing angles.
Relative to electron donors for bulk heterojunction organic solar cells (OSCs), electron acceptors that absorb strongly in the visible and even near‐infrared region are less well developed, which ...hinders the further development of OSCs. Fullerenes as traditional electron acceptors have relatively weak visible absorption and limited electronic tunability, which constrains the optical and electronic properties required of the donor. Here, high‐performance fullerene‐free OSCs based on a combination of a medium‐bandgap polymer donor (FTAZ) and a narrow‐bandgap nonfullerene acceptor (IDIC), which exhibit complementary absorption, matched energy levels, and blend with pure phases on the exciton diffusion length scale, are reported. The single‐junction OSCs based on the FTAZ:IDIC blend exhibit power conversion efficiencies up to 12.5% with a certified value of 12.14%. Transient absorption spectroscopy reveals that exciting either the donor or the acceptor component efficiently generates mobile charges, which do not suffer from recombination to triplet states. Balancing photocurrent generation between the donor and nonfullerene acceptor removes undesirable constraints on the donor imposed by fullerene derivatives, opening a new avenue toward even higher efficiency for OSCs.
High‐performance fullerene‐free single‐junction organic solar cells with power conversion efficiencies up to 12.5% are reported. Transient absorption spectroscopy reveals that exciting either the donor or acceptor component efficiently generates mobile charges, which do not suffer from recombination to triplet states.
The charge carriers of single‐junction solar cells can be fluently extracted and then collected by electrodes, leading to weak charge carrier accumulation and low energy loss (Eloss). However, in ...tandem solar cells (TSCs), it is a considerable challenge to obtain a balance between the densities of the holes and electrons extracted from the two respective subcells to facilitate an efficient recombination in the interconnecting layer (ICL). Herein, a charge‐carrier‐dynamic management strategy for inorganic perovskite/organic TSCs is proposed, centered on the simultaneous regulation of the defect states of CsPbI1.9Br1.1 perovskite in the front subcell and hole transport ability from the perovskite to ICL. The target hole density on the perovskite surface and the hole loss before reaching the ICL are significantly improved. As a result, the hole/electron density offset in the ICL can be effectively narrowed, leading to a balanced charge carrier recombination, which reduces the Eloss in TSCs. The resulting inorganic perovskite/organic 0.062‐cm2 TSC exhibits a remarkable power conversion efficiency (PCE) of 23.17% with an ultrahigh open‐circuit voltage (Voc) of 2.15 V, and the PCE of the 1.004‐cm2 device (21.69%) exhibited a weak size‐dependence. This charge‐carrier‐dynamic management strategy can also effectively enhance the operational and ultraviolet‐light stabilities of the TSCs.
A charge‐carrier‐dynamic management strategy for inorganic perovskite/organic tandem solar cells (TSCs) is conducted to narrow the hole/electron density offset in the interconnecting layer, which contributes to a balanced charge carrier recombination thus reducing the energy loss of the TSCs. A promising 23.17% power conversion efficiency, an ultrahigh open‐circuit voltage of 2.15 V, and robust operational stability are obtained.
Organic light-emitting diodes (OLEDs) have rapidly grown as one of the leading technologies for full-color display panels and eco-friendly lighting sources due to their outstanding features including ...superior color quality, wide viewing angle, mercury-free manufacture, fascinating flexibility,
etc.
A variety of materials, device architectures, as well as processing techniques have been investigated for optimizing device performance in order to fulfill the requirements of lighting and display applications. In this review, we first summarize the light emission mechanisms of electroluminescent materials. Then, the designed device architectures aiming at the realization of various light emission mechanisms are reviewed. An overview of recent advances in light extraction strategies is presented since all efficient OLEDs have a multi-thin-film structure, which leads to severe light trapping in devices. In addition, the progress of flexible OLEDs is reviewed from the aspect of flexible transparent electrodes because of their great potential in flexible displays. Most recent breakthroughs of solid-state lighting and displays are briefly addressed as well. A brief perspective on future research is also proposed for pursuing the commercialization of OLEDs.
Recent advances in organic light-emitting diodes toward smart lighting and displays are reviewed in terms of materials, devices, fabrication and applications.
A single‐junction polymer solar cell with an efficiency of 10.1% is demonstrated by using deterministic aperiodic nanostructures for broadband light harvesting with optimum charge extraction. The ...performance enhancement is ascribed to the self‐enhanced absorption due to collective effects, including pattern‐induced anti‐reflection and light scattering, as well as surface plasmonic resonance, together with a minimized recombination probability.
Polarization‐sensitive photodetectors are gaining numerous attention since polarization detection is important in geological remote sensing, atmospheric monitoring, military recon, and medical ...examination. Among various reported photoactive materials for photodetectors, metal halide perovskites have outstanding advantages such as tunable band gaps, excellent optoelectronic properties, and easy fabrication. Moreover, the characteristics of crystal structure anisotropy and controllable growth orientation of perovskite crystals endow the perovskite photodetector with the ability to identify light polarization states. This review outlines the recent research progress of perovskite photodetectors on polarization‐sensitive detection. Firstly, key device parameters of polarization‐sensitive detection are introduced. Then, the recent progress of polarization‐sensitive perovskite detectors in the field of linear and circular polarization is reviewed according to the different principles of polarization response. Finally, the challenges of polarization‐sensitive perovskite photodetector are discussed.
Polarization‐sensitive photodetectors are important in geological remote sensing, atmospheric monitoring, military recon, and medical examination. The review addresses the recent research progress of perovskite photodetectors on polarization‐sensitive detection in terms of key device parameters, linear and circular polarization via different principles of polarization response.
Because of their mechanical flexibility, organic light-emitting diodes (OLEDs) hold great promise as a leading technology for display and lighting applications in wearable electronics. The ...development of flexible OLEDs requires high-quality transparent conductive electrodes with superior bendability and roll-to-roll manufacturing compatibility to replace indium tin oxide (ITO) anodes. Here, we present a flexible transparent conductor on plastic with embedded silver networks which is used to achieve flexible, highly power-efficient large-area green and white OLEDs. By combining an improved outcoupling structure for simultaneously extracting light in waveguide and substrate modes and reducing the surface plasmonic losses, flexible white OLEDs exhibit a power efficiency of 106 lm W–1 at 1000 cd m–2 with angular color stability, which is significantly higher than all other reports of flexible white OLEDs. These results represent an exciting step toward the realization of ITO-free, high-efficiency OLEDs for use in a wide variety of high-performance flexible applications.
Rapid progress in the power conversion efficiency (PCE) of polymer solar cells (PSEs) is beneficial from the factors that match the irradiated solar spectrum, maximize incident light absorption, and ...reduce photogenerated charge recombination. To optimize the device efficiency, a nanopatterned ZnO:Al2O3 composite film is presented as an efficient light‐ and charge‐manipulation layer (LCML). The Al2O3 shells on the ZnO nanoparticles offer the passivation effect that allows optimal electron collection by suppressing charge‐recombination loss. Both the increased refractive index and the patterned deterministic aperiodic nanostructure in the ZnO:Al2O3 LCML cause broadband light harvesting. Highly efficient single‐junction PSCs for different binary blends are obtained with a peak external quantum efficiency of up to 90%, showing certified PCEs of 9.69% and 13.03% for a fullerene blend of PTB7:PC71BM and a nonfullerene blend, FTAZ:IDIC, respectively. Because of the substantial increase in efficiency, this method unlocks the full potential of the ZnO:Al2O3 LCML toward future photovoltaic applications.
Highly efficient polymer solar cells based on nanopatterned ZnO:Al2O3 composite film achieve a peak external quantum efficiency up to 90% and a certified power conversion efficiency of 13.03%. Optical and electrical studies demonstrate enhanced light harvesting due to passivation‐ and dipole‐induced suppression of charge recombination loss and broadband absorption enhancement.
Highly power‐efficient white organic light‐emitting diodes (OLEDs) are still challenging to make for applications in high‐quality displays and general lighting due to optical confinement and energy ...loss during electron‐photon conversion. Here, an efficient white OLED structure is shown that combines deterministic aperiodic nanostructures for broadband quasi‐omnidirectional light extraction and a multilayer energy cascade structure for energy‐efficient photon generation. The external quantum efficiency and power efficiency are raised to 54.6% and 123.4 lm W−1 at 1000 cd m−2. An extremely small roll‐off in efficiency at high luminance is also obtained, yielding a striking value of 106.5 lm W−1 at 5000 cd m−2. In addition to a substantial increase in efficiency, this device structure simultaneously offers the superiority of angular color stability over the visible wavelength range compared to conventional OLEDs. It is anticipated that these findings could open up new opportunities to promote white OLEDs for commercial applications.
Highly efficient, white, organic light‐emitting diodes are achieved by combining deterministic aperiodic nanostructures for broadband light extraction with a multilayer energy cascade structure for energy‐efficient photon generation. This results in light‐emitting diodes with a record power efficiency of 123.4 lm W−1 at 1000 cd m−2 with superior color stability and extremely small efficiency roll‐off.
PDF
