Porphyrinic Metal–Organic Framework Quantum Dots for Stable n–i–p Perovskite Solar Cells

As the power-conversion efficiency (PCE) of organic–inorganic lead halide perovskite solar cells (PSCs) is approaching the theoretical maximum, the most crucial issue concerns long-term ambient stability. Here, the application of PCN-224 quantum dots (QDs) is reported, a typical Zr-based porphyrinic metal–organic framework (MOF), to enhance the ambient stability of PSCs. PCN-224 QDs with abundant Lewis-base groups (e.g., CO, C−N, CN) contribute to high-quality perovskite films with enlarged grain size and reduced defect density by interaction with under-coordinated Pb²⁺. Meanwhile, PCN-224 QDs enable the well-matched energy level at the perovskite/hole transport layer (HTL) interface, thereby facilitating hole extraction and transport. More importantly, PCN-224 QDs-treated HTL can capture Li⁺ from bis(trifluoromethanesulfonyl)imide additive, leading to the reduced aggregation and less direct contact with moisture for hygroscopic Li-TFSI. Moreover, PCN-224 QDs mitigated Li⁺ ion migration into the perovskite layer, thus avoiding the formation of deleterious defects. The resultant devices yield a champion PCE of 22.51%, along with substantially improved durability, including humidity, thermal and light soaking stabilities. The findings provide a new approach toward efficient and stable PSCs by applying MOF QDs.     

Manifestation of Flexible p–i–n Solar Cells Fabricated Using HWCVD in WSN Application

Wireless Personal Communications - The wireless sensor network (WSN) consist of battery-powered sensor nodes which are self-configured and are deployed for monitoring several physical or...     

Analysis of quantum efficiency and optical enhancement in amorphous Si p–i–n solar cells

The effect of i-layer thickness, tin oxide texture, and back reflector (BR) on optical enhancement has been systematically studied in a series of 20 a-Si p–i–n solar cells. The internal quantum efficiency has been analyzed by a simple model based on the work of Schade and Smith. The enhancement of optical absorption is characterized by m, a wavelength-dependent fitting parameter representing the increase in optical pathlength relative to the i-layer thickness d. Solar cells with an Al BR have negligible optical enhancement, with m < 1.5, consistent with large parasitic absorption at the Al/Si interface as reported by others. Solar cells on highly textured SnO₂ with ZnO/Al or ZnO/Ag BR have peak values of m ∼ 3–4, with ZnO/Ag having slightly larger values than ZnO/Al. It was found that m has a strong dependence on the product αd, and that maximum values of m increase with reflectivity of the BR. It is shown that a major source of parasitic absorption loss at long wavelengths is light trapping in the textured SnO₂ front contact. Copyright © 2002 John Wiley & Sons, Ltd.     

A low drive voltage,transparent, metal-free n–i–p electrophosphorescent light emitting diode

We demonstrate a transparent, inverted, electrophosphorescent n–i–p organic light emitting diode (OLED) exhibiting a luminance of 500 cd/m² at 3.1 V, and with a luminous power efficiency of 23 lm/W when light emitted from both top and bottom surfaces is summed. We find that 10% more light is emitted from the top surface; hence a power efficiency of 12 lm/W is obtained for a device viewed through the top, transparent contact. This device, with applications to head-up and displays employing n-type Si driver circuitry, has significantly higher power efficiency and lower drive voltage than undoped fluorescent inverted OLEDs. Efficient injection of both electrons and holes is made possible by controlled n- and p-doping of the transport layers with high doping levels. The light emitting region is protected from ITO sputtering damage by a 210 nm thick p-doped hole transport layer. The transparency of the device at the peak OLED emission wavelength of 510 nm is (80 ± 5)%.     

Dual Sub-Cells Modification Enables High-Efficiency n–i–p Type Monolithic Perovskite/Organic Tandem Solar Cells

Monolithic perovskite/organic tandem solar cells (POTSCs) have attracted increasing attention owing to ability to overcome the Shockley–Queisser limit. However, compromised sub-cells performance limits the tandem device performance, and the power conversion efficiency (PCE) of POTSCs is still lower than their single-junction counterparts. Therefore, optimized sub-cells with minimal energy loss are desired for producing high-efficiency POTSCs. In this study, an ionic liquid, methylammonium acetate (MAAc), is used to modify wide-bandgap perovskite sub-cells (WPSCs), and bathocuproine (BCP) is used to modify small-bandgap organic solar cells. The Ac⁻ group of MAAc can effectively heal the Pb defects in the all-inorganic perovskite film, which enables a high PCE of 17.16% and an open-circuit voltage (V_oc) of 1.31 V for CsPbI_2.2Br_0.8-based WPSCs. Meanwhile, the BCP film, inserted at the ZnO/organic bulk-heterojunction (BHJ) interface, acts as a space layer to prevent direct contact between ZnO and the BHJ while passivating the surface defects of ZnO, thereby mitigating ZnO defect-induced efficiency loss. As a result, PM6:CH1007-based SOSCs exhibit a PCE of 15.46%. Integrating these modified sub-cells enable the fabrication of monolithic n–i–p structured POTSCs with a maximum PCE of 22.43% (21.42% certified), which is one of the highest efficiencies in such type of POTSCs.     

Subnanosecond Avalanche Switching Simulations of n+–n–n+ Silicon Structures

Semiconductors - The simulations of recently discovered effect of subnanosecond avalanche switching of Si n+−n−n+-structures have been performed. The electric field in...     

Dual Role of Cu-Chalcogenide as Hole-Transporting Layer and Interface Passivator for p–i–n Architecture Perovskite Solar Cell

Inorganic hole-transport layers (HTLs) are widely investigated in perovskite solar cells (PSCs) due to their superior stability compared to the organic HTLs. However, in p–i–n architecture when these inorganic HTLs are deposited before the perovskite, it forms a suboptimal interface quality for the crystallization of perovskite, which reduces device stability, causes recombination, and limits the power conversion efficiency of the device. The incorporation of an appropriate functional group such as sulfur-terminated surface on the HTL can enhance the interface quality due to its interaction with perovskite during the crystallization process. In this work, a bifunctional Al-doped CuS film is wet-deposited as HTL in p–i–n architecture PSC, which besides acting as an HTL also improves the crystallization of perovskite at the interface. Urbach energy and light intensity versus open-circuit voltage characterization suggest the formation of a better-quality interface in the sulfide HTL–perovskite heterojunction. The degradation behavior of the sulfide-HTL-based perovskite devices is studied, where it can be observed that after 2 weeks of storage in a controlled environment, the devices retain close to 95% of their initial efficiency.     

Stabilization of α-phase FAPbI3 via Buffering Interfacial Region for Efficient p–i–n Perovskite Solar Cells

Formamidinium lead triiodide (FAPbI₃) with an ideal bandgap and good thermal stability has received wide attention and achieved a record efficiency of 26% in n–i–p (regular) perovskite solar cells (PSCs). However, imperfect FAPbI₃ formation on the typical hole transport layer (HTL), high interfacial trap-state density, and unfavorable energy alignment between the HTL and FAPbI₃ result in the inferior photovoltaic performance of p–i–n (inverted) PSCs with FAPbI₃ absorber. Herein, the α-phase FAPbI₃ is stabilized by constructing a buffer interface region between the NiO_x HTL and FAPbI₃, which not only diminishes NiO_x/FAPbI₃ interfacial reactions and defects but also facilitates carrier transport. Upon the construction of a buffer interface region, FAPbI₃ inverted PSC exhibits a high-power conversion efficiency of 23.56% (certified 22.58%) and excellent stability, retaining 90.7% of its initial efficiency after heating at 80 °C for 1000 h and 84.6% of the initial efficiency after operating at the maximum power point under continuous illumination for 1100 h. Besides, as a light-emitting diode device, the FAPbI₃ inverted PSC can be directly lit with an external quantum efficiency of 1.36%. This study provides a unique and efficient strategy to advance the application of α-phase FAPbI₃ in inverted PSCs.     

Highly Stable n–i–p Structured Formamidinium Tin Triiodide Solar Cells through the Stabilization of Surface Sn2+ Cations

Improving the performance, reproducibility, and stability of Sn-based perovskite solar cells (PSCs) with n–i–p structures is an important challenge. Spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], a hole transporting material (HTM) with n–i–p structure, requires the oxygen exposure after addition of Li-TFSI [Lithium bis(trifluoromethanesulfonyl)imide] as a dopant to increase the hole concentration. In Sn-based PSC, Sn²⁺ is easily oxidized to Sn⁴⁺ under such a condition, resulting in a sharp decrease in efficiency. Herein, a formamidinium tin triiodide (FASnI₃)-based PSCs fabricated using DPI-TPFB [4-Isopropyl-4′-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate] instead of Li-TFSI are reported as a dopant in Spiro-OMeTAD. The DPI-TPFB enables the fabrication of PSCs with an efficiency of up to 10.9%, the highest among FASnI₃-based PSCs with n–i–p structures. Moreover, ≈80% of the initial efficiency is maintained even after 1,597 h under maximum power point tracking conditions. In particular, the encapsulated device does not show any decrease in efficiency even after holding for 50 h in the 85 °C/85% RH condition. The high efficiency and excellent stability of PSCs prepared by doping with DPI-TPFB are attributed to not only increasing electrical conductivity by acting as a Lewis acid, but also stabilizing Sn²⁺ through coordination with Sn²⁺ on the surface of FASnI₃.     

Amplification of terahertz radiation in a plasmon <Emphasis Type="Italic">n–i–p–i</Emphasis> graphene structure with charge-carrier injection

The absorption/amplification spectrum of terahertz radiation in inhomogeneous graphene (n–i–p–i structure) with a periodic dual metal grating is theoretically investigated. It is shown that the amplification of terahertz radiation sharply increases at the plasmon-resonance frequency, when losses due to electron scattering and emission are balanced by the plasmon gain (related to the stimulated radiative interband recombination of electron–hole pairs in the inverted region of graphene).     

Electrosynthesis of organic–inorganic compounds (p–n heterojunction)

An electrochemical deposition procedure by cyclic voltammetry, in an electrolyte solution was adopted for the preparation of thin films of polypyrrole–gallium arsenide composite materials. The properties of the composite layers were studied by cyclic voltammetry, electrochemical impedance spectroscopy and photoelectrochemical measurements. The p- and n-type semiconductor behaviour of the polypyrrole (PPy) and gallium arsenide (GaAs) were studied by photocurrent measurements. It was found that the composite material (PPy–GaAs) had a (p–n) heterojunction behaviour.     

Solution-processed hybrid p–n junction vertical diode

Solution-processed n-ZnO/p-poly(3,3′′′-didodecylquaterthiophene) (PQT-12) vertical p–n junction diodes were prepared on ITO-coated glass. A continuous film of ZnO nanoparticles was grown on the ITO glass by dip-coating and subsequent heat treatment of a zinc acetate film. PQT-12 was then spin-coated to form the ZnO/PQT-12 diode. Gold was chosen as the top electrode to complement ITO for this diode. The microstructures of ZnO films are studied by atomic force microscopy (AFM) and show a continuous, dense layer of ZnO nanoparticles. The current–voltage (I–V) measurement shows that the maximum current density for this p–n junction diode is 400 A/cm², which is much higher than previously reported polymer diodes. Capacitance–voltage (C–V) data also provide evidence of formation of the p–n junction. The rectification was characterized by observation of full input-half output waves. Data indicate that these devices can operate up to frequencies of 14 MHz under ambient environment conditions. This rectification frequency is higher than other reported polymer Schottky diodes under these conditions. Turnon voltages of this diode are also much lower than for the reported polymer diodes.     

μc—Si：H p—i—n薄膜太阳能电池中i层的设计分析

通过应用Ｓｃｈａｒｆｅｔｔｅｒ－Ｇｕｍｍｅｌ解法数值求解Ｐｏｉｓｓｏｎ方程，对热平衡μｃ－Ｓｉ：Ｈ ｐ－ｉ－ｎ薄膜太阳能电池进行计算机数值模拟。结果表明，光吸收体ｉ层或Ｐ型择杂都会在ｉ层中造成低场区而不利于光生载流子传输，指出μｃ－ＳｉＨ：ｐ－ｉ－ｎ太阳能电池制造中采用补偿μｃ－Ｓｉ：Ｈ薄膜充当吸收体ｉ层能提高长波（〉８００ｎｍ）载流子收集效率，从而增大电池的短路电流。     

CdTe p—i—n薄膜太阳能电池热平衡态数值分析

通过应用Ｓｃｈａｒｆｅｔｔｅｒ－Ｇｕｍｍｅｌ解法数值求解Ｐｏｉｓｓｏｎ方程，对热平衡态ｐ（ＺｎＴｅ）／ｉ（ＣｄＴｅ）／ｎ（ＣｄＳ）薄膜太阳能电池进行计算机数值模拟。结果表明，ｐ（ＺｎＴｅ）／ｉ（ＣｄＴｅ）／ｎ（ＣｄＳ）的能带结构有利于光生载流子传输与收集，ＣｄＴｅ中高内建场提高了光生载流子通过有源区的输运能力，对ＣｄＴｅ进行适量Ｐ型掺杂还能提高其电池的短波收集效率。     

Interfacial dipole in organic p–n junction to realize write-once–read-many-times memory

A new approach is exploited to realize nonvolatile organic write-once–read-many-times (WORM) memory based on copper phthalocyanine (CuPc)/hexadecafluoro-copper-phthalocyanine (F₁₆CuPc) p–n junction. The as-fabricated device is found to be at its ON state and can be programmed irreversibly to the OFF state by applying a negative bias. The WORM device exhibits a high ON/OFF current ratio of up to 2.6 × 10⁴. An interfacial dipole layer is testified to be formed and destructed at the p–n junction interface for the ON and OFF states, respectively. The ON state at positive voltage region is attributed to the efficient hole and electron injection from the respective electrodes and then recombination at the CuPc/F₁₆CuPc interface, and the transition of the device to the OFF state results from the destruction of the interfacial dipole layer and formation of an insulating layer which restricts charge carrier recombination at the interface.     

i上音乐联想i908

联想的i系列手机一向都是年轻消费者追捧的对象，该系列的手机在外形上大部采用了最新颖甚至可以说是夸张的设计．另外．出色的多媒体功能也是一大是卖点。最新推出的i908保留了很多优点．在细节上也做了不少改进，更让人爱不释的。[编者按]     

i,Touch 联想i817

在去年的十一黄金周,联想(Lenovo)粉时尚系列i807凭着时尚的设计与高性价比着实“火“了一把。不料时隔一年之后的今日。联想再次想到了这位昔日的功臣,推出了它的升级版i817。虽然不免有炒冷饭的嫌疑,但能把冷饭做得如此可口,也算是功力深厚了。     

Cross-sectional Scanning Probe Microscopy of GaN-based p–n heterostructures

In this work, the structural and electrical properties of a GaN-based p–n heterostructure are studied using cross-sectional Atomic Force Microscopy, Friction Force Microscopy, Electrical Force Gradient Microscopy, and Surface Potential Microscopy. Using Atomic Force Microscopy and Friction Force Microscopy, we were able to identify and measure the thickness of the layers present in the heterostructures. The electrical conductivity type of the different layers as well as the p–n junction, and piezoelectric fields were identified and studied using Electric Force Gradient Microscopy and Surface Potential Microscopy.     

Solution processable organic p–n junction bilayer vertical photodiodes

Organic p–n bilayer photodiodes were produced by solution casting poly(3-hexylthiophene) (P3HT) from chlorobenzene and phenyl-C₆₁-butyric acid methyl ester (PCBM):poly(4-chlorostyrene) (PClS) blends from the nearly orthogonal solvent dichloromethane onto flexible indium tin oxide (ITO)/polyester as a substrate. This is the first demonstration of PCBM–inert polymer blends for such a device. The electron mobility of a 90% PCBM–10% PClS blend was 3.5 × 10^?3 cm²/V s in a field-effect transistor. The diodes showed a rectification ratio of 2.0 × 10³ at ±2.0 V with a forward bias current density as high as 340 μA/cm² at 2.0 V in the dark. Irradiation with various light sources (0.013–291 mW/cm²) under ambient atmosphere generated a linear increase in photocurrent. Photodiodes with thinner active layers showed larger photocurrent and relative photoresponse, probably because of lower series resistance and lower recombination probability. The reverse bias response was less dependent on device area than the forward bias response. Photocurrents from multiple devices in parallel were additive as expected. The results demonstrate a simple fabrication route to light detectors compatible with solution processes and flexible substrates.     

Bias-Selectable Si Nanowires/PbS Nanocrystalline Film n–n Heterojunction for NIR/SWIR Dual-Band Photodetection

In this study, a solution method derived dual-band photodetector (PD) based on silicon nanowires /PbS nanocrystalline film n–n heterojunction, which exhibits typical bias-selectable spectral response in both near-infrared (NIR) and short-wave infrared (SWIR) bands, is presented. It is found that by adjusting the polarity of the bias voltage, the photoresponse of the device can be switched between three operation modes. The device exhibits high responsivities of 2100 mA W⁻¹ at −0.15 V and 31 mA W⁻¹ at 0 V, respectively, in the NIR region. Remarkably, the maximum responsivity and detectivity under 2000 nm illumination are determined as 290 mA W⁻¹ and 2.4 × 10¹⁰ Jones, comparable to or even better than some PbS commercial PDs. The enhanced performance comes from the improved optical absorption and higher efficiency of charge separation and collection owing to the heterojunction geometry. It's also revealed that the bias-controllable spectral response is attributed to the selectively transportation of photocarriers across the junction barrier. The study demonstrates the capability of detecting two distinct IR regions with the same pixel, which has great potential in future optoelectronic systems for IR imaging applications.