Halide lead perovskites have attracted increasing attention in recent years for ionizing radiation detection due to their strong stopping power, defect-tolerance, large mobility-lifetime (μτ) ...product, tunable bandgap and simple single crystal growth from low-cost solution processes. In this review, we start with the requirement of material properties for high performance ionizing radiation detection based on direct detection mechanisms for applications in X-ray imaging and γ-ray energy spectroscopy. By comparing the performances of halide perovskites radiation detectors with current state-of-the-art ionizing radiation detectors, we show the promising features and challenges of halide perovskites as promising radiation detectors.
Organolead trihalide perovskite is an emerging low-cost, solution-processable material with a tunable bandgap from the violet to near-infrared, which has attracted a great deal of interest for ...applications in high-performance optoelectronic devices. Here, we present hybrid perovskite single-crystal photodetectors that have a very narrow spectral response with a full-width at half-maximum of <20 nm. The response spectra are continuously tuned from blue to red by changing the halide composition and thus the bandgap of the single crystals synthesized by solution processes. The narrowband photodetection can be explained by the strong surface-charge recombination of the excess carriers close to the crystal surfaces generated by short-wavelength light. The excess carriers generated by below-bandgap excitation locate away from the surfaces and can be much more efficiently collected by the electrodes, assisted by the applied electric field. This provides a new design paradigm for a narrowband photodetector with broad applications where background noise emission needs to be suppressed.
The large photocurrent hysteresis observed in many organometal trihalide perovskite solar cells has become a major hindrance impairing the ultimate performance and stability of these devices, while ...its origin was unknown. Here we demonstrate the trap states on the surface and grain boundaries of the perovskite materials to be the origin of photocurrent hysteresis and that the fullerene layers deposited on perovskites can effectively passivate these charge trap states and eliminate the notorious photocurrent hysteresis. Fullerenes deposited on the top of the perovskites reduce the trap density by two orders of magnitude and double the power conversion efficiency of CH(3)NH(3)PbI(3) solar cells. The elucidation of the origin of photocurrent hysteresis and its elimination by trap passivation in perovskite solar cells provides important directions for future enhancements to device efficiency.
New parallel computing architectures based on neuromorphic computing are needed due to their advantages over conventional computation with regards to real‐time processing of unstructured sensory data ...such as image, video, or voice. However, developing artificial neuromorphic system remains a challenge due to the lack of electronic synaptic devices, which can mimic all the functions of biological synapses with low energy consumption. Here it is reported that two‐terminal organometal trihalide perovskite (OTP) synaptic devices can mimic the neuromorphic learning and remembering process. Various functions known in biological synapses are demonstrated in OTP synaptic devices including four forms of spike‐timing‐dependent plasticity (STDP), spike‐rate‐dependent plasticity (SRDP), short‐term plasticity (STP) and long‐term potentiation (LTP)), and learning‐experience behavior. The excellent photovoltaic property of the OTP devices also enables photo‐read synaptic functions. The perovskite synapse has the potential of low energy consumption of femto‐Joule/(100 nm)2 per event, which is close to the energy consumption of biological synapses. The demonstration of energy‐efficient OTP synaptic devices opens a new plausible application of OTP materials into neuromorphic devices, which offer the high connectivity and high density required for biomimic computing.
Low temperature, solution‐processed two‐terminal MAPbI3 devices work as ideal candidates for memristors and synaptic devices to mimic biological synapses. These two‐terminal organometal trihalide perovskite synaptic devices can mimic the neuromorphic learning and remembering process. Many functions of biological synapse are visualized in these perovskite synaptic devices.
Tunneling contacts made of any insulating polymers, a champion technology in silicon solar cells, are shown to increase the stabilized efficiency of perovskite solar cells (PSCs) to 20.3%. The ...tunneling layers spatially separate photo‐generated electrons and holes at the perovskite‐cathode interface and reduce charge recombination. The tunneling layers made of hydrophobic polymers also significantly enhance the resistance of PSCs to water‐caused damage.
Photon recycling, that is, iterative self-absorption and re-emission by the photoactive layer itself, has been speculated to contribute to the high open-circuit voltage in several types of high ...efficiency solar cells. For organic-inorganic halide perovskites that have yielded highly efficient photovoltaic devices, however, it remains unclear whether the photon recycling effect is significant enough to improve solar cell efficiency. Here we quantitatively evaluate the re-absorption and re-emission processes to determine photon recycling efficiency in hybrid perovskite with its single crystals by measuring the ratio of the re-emitted photons to the initially excited photons, which is realized by modulating their polarization to differentiate them. The photon recycling efficiencies are revealed to be less than 0.5% in CH
NH
PbI
and CH
NH
PbBr
single crystals under excitation intensity close to one sun, highlighting the intrinsically long carrier recombination lifetime instead of the photon-recycling-induced photon propagation as the origin of their long carrier diffusion length.
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