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The scalable and low-cost room temperature (RT) synthesis for pure-iodine all-inorganic perovskite colloidal quantum dots (QDs) is a challenge due to the phase transition induced by thermal unequilibrium. Here, we introduce a direct RT strongly confined spontaneous crystallization strategy in a Cs-deficient reaction system without polar solvents for synthesizing stable pure-iodine all-inorganic tin-lead (Sn-Pb) alloyed perovskite colloidal QDs, which exhibit bright yellow luminescence. By tuning the ratio of Cs/Pb precursors, the size confinement effect and optical band gap of the resultant CsSnxPb1-xI3 perovskite QDs can be well controlled. This strongly confined RT approach is universal for wider bandgap bromine- and chlorine-based all-inorganic and iodine-based hybrid perovskite QDs. The alloyed CsSn0.09Pb0.91I3 QDs show superior yellow emission properties with prolonged carrier lifetime and significantly increased colloidal stability compared to the pristine CsPbI3 QDs, which is enabled by strong size confinement, Sn2+ passivation and enhanced formation energy. These findings provide a RT size-stabilized synthesis pathway to achieve high-performance pure-iodine all-inorganic Sn-Pb mixed perovskite colloidal QDs for optoelectronic applications. Photoactive pure-iodine all-inorganic colloidal perovskite quantum dots (QDs) are attractive for optoelectronic applications, however their synthesis at room temperature is challenging. Here the authors report a room temperature strongly confined strategy to synthesize CsSnxPb1-xI3 QDs. [ABSTRACT FROM AUTHOR]

Mixed tin-lead perovskite solar cells have driven a lot of passion for research because of their vital role in all-perovskite tandem solar cells, which hold the potential for achieving higher efficiencies compared to single-junction counterparts. However, the pronounced disparity in crystallization processes between tin-based perovskites and lead-based perovskites, coupled with the easy Sn2+ oxidation, has long been a dominant factor contributing to high defect densities. In this study, we propose a multidimensional strategy to achieve efficient tin-lead perovskite solar cells by employing a functional N-(carboxypheny)guanidine hydrochloride molecule. The tailored N-(carboxypheny)guanidine hydrochloride molecule plays a pivotal role in manipulating the crystallization and grain growth of tin-lead perovskites, while also serving as a preservative to effectively inhibit Sn2+ oxidation, owing to the strong binding between N-(carboxypheny)guanidine hydrochloride and tin (II) iodide and the elevated energy barriers for oxidation. Consequently, single-junction tin-lead cells exhibit a stabilized power conversion efficiency of 23.11% and can maintain 97.45% of their initial value even after 3500 h of shelf storage in an inert atmosphere without encapsulation. We further integrate tin-lead perovskites into two-terminal monolithic all-perovskite tandem cells, delivering a certified efficiency of 27.35%.The disparity in crystallization processes between tin- and lead-based perovskites has been a dominant factor contributing to high defect densities. Here, authors employ a functional molecule to inhibit tin oxidation, realizing monolithic all-perovskite tandems with certified efficiency over 27%. [ABSTRACT FROM AUTHOR]

All-perovskite tandem solar cells hold great promise in surpassing the Shockley–Queisser limit for single-junction solar cells1–3. However, the practical use of these cells is currently hampered by the subpar performance and stability issues associated with mixed tin–lead (Sn–Pb) narrow-bandgap perovskite subcells in all-perovskite tandems4–7. In this study, we focus on the narrow-bandgap subcells and develop an all-in-one doping strategy for them. We introduce aspartate hydrochloride (AspCl) into both the bottom poly(3,4-ethylene dioxythiophene)–poly(styrene sulfonate) and bulk perovskite layers, followed by another AspCl posttreatment. We show that a single AspCl additive can effectively passivate defects, reduce Sn4+ impurities and shift the Fermi energy level. Additionally, the strong molecular bonding of AspCl–Sn/Pb iodide and AspCl–AspCl can strengthen the structure and thereby improve the stability of Sn–Pb perovskites. Ultimately, the implementation of AspCl doping in Sn–Pb perovskite solar cells yielded power conversion efficiencies of 22.46% for single-junction cells and 27.84% (27.62% stabilized and 27.34% certified) for tandems with 95% retention after being stored in an N2-filled glovebox for 2,000 h. These results suggest that all-in-one AspCl doping is a favourable strategy for enhancing the efficiency and stability of single-junction Sn–Pb perovskite solar cells and their tandems.AspCl doping in Sn–Pb perovskite solar cells improves their performance and stability. [ABSTRACT FROM AUTHOR]

Highlights: A versatile material-antimony potassium tartrate is added to wide-bandgap perovskite cells for the first time. Inverted wide-bandgap perovskite solar cells with a structure of ITO/MeO-2PACz/perovskite/C60/ALD-SnO2/Cu yield a champion power conversion efficiency of 20.35%. A perovskite/perovskite four-terminal tandem solar cell with efficiency of 26.3% is achieved. Wide-bandgap (WBG) perovskites have been attracting much attention because of their immense potential as a front light-absorber for tandem solar cells. However, WBG perovskite solar cells (PSCs) generally exhibit undesired large open-circuit voltage (VOC) loss due to light-induced phase segregation and severe non-radiative recombination loss. Herein, antimony potassium tartrate (APTA) is added to perovskite precursor as a multifunctional additive that not only coordinates with unbonded lead but also inhibits the migration of halogen in perovskite, which results in suppressed non-radiative recombination, inhibited phase segregation and better band energy alignment. Therefore, a APTA auxiliary WBG PSC with a champion photoelectric conversion efficiency of 20.35% and less hysteresis is presented. They maintain 80% of their initial efficiencies under 100 mW cm−2 white light illumination in nitrogen after 1,000 h. Furthermore, by combining a semi-transparent WBG perovskite front cell with a narrow-bandgap tin–lead PSC, a perovskite/perovskite four-terminal tandem solar cell with an efficiency over 26% is achieved. Our work provides a feasible approach for the fabrication of efficient tandem solar cells. [ABSTRACT FROM AUTHOR]

Highlights: Through materials analysis and theoretical calculations, the defects of CsSnI3 nanowires (NWs) were effectively passivated via incorporating 1-butyl-2,3-dimethylimidazolium chloride into perovskites. The high-performance CsSnI3 NW photodetectors (PDs) were achieved with a responsivity of up to 0.237 A W−1, a high detectivity of 1.18 × 1012 Jones and a linear dynamic range of 180 dB. These values are comparable to the reported high-performance Pb-based perovskite PDs and higher than those of the Pb-free perovskite PDs. Our unpackaged devices exhibit ultra-high stability with no degradation after 60 days of storage in air (25 °C, 50% humidity). In recent years, Pb-free CsSnI3 perovskite materials with excellent photoelectric properties as well as low toxicity are attracting much attention in photoelectric devices. However, deep level defects in CsSnI3, such as high density of tin vacancies, structural deformation of SnI6− octahedra and oxidation of Sn2+ states, are the major challenge to achieve high-performance CsSnI3-based photoelectric devices with good stability. In this work, defect passivation method is adopted to solve the above issues, and the ultra-stable and high-performance CsSnI3 nanowires (NWs) photodetectors (PDs) are fabricated via incorporating 1-butyl-2,3-dimethylimidazolium chloride salt (BMIMCl) into perovskites. Through materials analysis and theoretical calculations, BMIM+ ions can effectively passivate the Sn-related defects and reduce the dark current of CsSnI3 NW PDs. To further reduce the dark current of the devices, the polymethyl methacrylate is introduced, and finally, the dual passivated CsSnI3 NWPDs show ultra-high performance with an ultra-low dark current of 2 × 10–11 A, a responsivity of up to 0.237 A W−1, a high detectivity of 1.18 × 1012 Jones and a linear dynamic range of 180 dB. Furthermore, the unpackaged devices exhibit ultra-high stability in device performance after 60 days of storage in air (25 °C, 50% humidity), with the device performance remaining above 90%. [ABSTRACT FROM AUTHOR]

Large single crystals serve as an ideal platform for investigating intrinsic material properties and optoelectronic applications. Here we develop a method, namely, room-temperature liquid diffused separation induced crystallization that uses silicone oil to separate the solvent from the perovskite precursors, to grow high-quality perovskite single crystals. The growth kinetics of perovskite single crystals using this method is elucidated, and their structural and optoelectronic properties are carefully characterized. The resultant perovskite single crystals, taking CH3NH3PbBr3 as an example, exhibit approximately 1 µs lifetime, a low trap density of 4.4 × 109 cm−3, and high yield of 92%, which are appealing for visible light or X-ray detection. We hope our findings will be of great significance for the continued advancement of high-quality perovskite single crystals, through a better understanding of growth mechanisms and their deployment in various optoelectronics. The diffused separation induced crystallization strategy presents a major step forward for advancing the field on perovskite single crystals. Perovskites are appealing for optoelectronics, but high-quality perovskite single crystals should be grown at low temperature to minimize trap density. Here, the authors report a room-temperature liquid-diffused-induced crystallization for growth of high-quality hybrid perovskite single crystals. [ABSTRACT FROM AUTHOR]

Organic polymer solar cells (OSCs) and organic-inorganic hybrid perovskite solar cells (PSCs) have achieved notable progress over the past several years. A central topic in these fields is exploring electronically efficient, stable and effective hole-transporting layer (HTL) materials. The goal is to enhance hole-collection ability, reduce charge recombination, increase built-in voltage, and hence improve the performance as well as the device stability. Transition metal oxides (TMOs) semiconductors such as NiO, CuO, CrO, MoO, WO, and VO, have been widely used as HTLs in OSCs. These TMOs are naturally adopted into PSC as HTLs and shows their importance. There are similarities, and also differences in applying TMOs in these two types of main solution processed solar cells. This concise review is on the recent developments of transition metal oxide HTL in OSCs and PSCs. The paper starts from the discussion of the cation valence and electronic structure of the transition metal oxide materials, followed by analyzing the structure-property relationships of these HTLs, which we attempt to give a systematic introduction about the influences of their cation valence, electronic structure, work function and film property on device performance. [ABSTRACT FROM AUTHOR]

Alternating-current-driven ZnO-based light-emitting diodes (LEDs) with an Au/ZnMgO/ZnO/ZnMgO/GaN/In structure have been fabricated. Both polarity-controlled electroluminescence (EL) and ultraviolet emission were achieved when driven by an alternating current (AC) under a much lower root-mean-square voltage than that of conventional inorganic AC thin-film electroluminescent devices. This ZnO-based LED can be regarded as a series incorporating a metal-insulator-semiconductor diode and a p- i- n diode. The EL mechanisms were discussed in terms of the band diagrams and carrier transport behavior with reference to the semiconductor heterojunction theory. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

An organic-inorganic photodetector based on poly(3,4-ethylenedioxythiophene) (PEDOT:PSS)/SnO microwires p- n heterojunction has been fabricated. The photodetector reveals excellent rectifying behavior, and it exhibits a significant photoresponse to blue light of 450 nm without bias, which indicates its high potential application values. The PEDOT:PSS/SnO heterojunction photodetector shows excellent stability and reproducible characteristics from the time-dependent photoresponse spectrum. The mechanism of the blue-sensitive photodetector is discussed in terms of band diagram of the heterojunction and the material properties. [ABSTRACT FROM AUTHOR]

Tower-like GaN nanowires were successfully fabricated on Au-coated Si substrates by chemical vapor deposition. The tower-like nanowire consisted of a nanowire at the center and microcrystal layers stacked one by one around the nanowire. The tower-like nanowires grew along the [0001] direction, and the exposed surfaces of the microcrystal layers are [InlineEquation not available: see fulltext.] and [InlineEquation not available: see fulltext.] facets. The growth mechanism of the tower-like GaN nanowires was proposed. The field emission property of tower-like GaN nanowires was tested. Due to the sharp tips, nearly vertical alignment and rough surfaces caused by the microcrystal layers, the tower-like GaN nanowires show excellent performance in field emission with a turn-on field of 2.44 V/μm which is lower than those of other GaN one-dimensional (1D) nanomaterials. PACS: 81.15.Gh; 68.37.Lp; 68.37.Vj [ABSTRACT FROM AUTHOR]

A novel concept based on the use of solutions containing already qualified crystalline antimony-doped tin oxide SnO:Sb (ATO) nanoparticles has been developed. ATO nanoparticles are decorated by reduced graphene oxide (rGO) through a hydrothermal synthesis method. The electrical and optical properties of the graphene oxide films are investigated systematically. The sheet resistance ( R) of the ATO-rGO films decreases with the increase in the rGO content in the precursor solution. The R can be decreased after the ATO-rGO films annealing in the air for 1 h and can be further decreased by depositing Au on the surface of the films. The optimum property of the ATO-rGO film shows that the R is 80 Ω/□ and the transmittance is about 70 %. The ATO-rGO films are used as the anode of the organic solar cells. The anode film impact on the performance of the devices is studied. Finally, the power conversion efficiency (PCE) of the device based on the poly-(3-hexylthiophene): [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) blended is 1.85 %, and the PCE of the device based on the poly-benzo[1,2-b:4,5-b′] dithio-phene thieno[3,4-b] thiophene:PCBM blended is 3.4 %. [ABSTRACT FROM AUTHOR]

Highly c-axis oriented ZnO thin films have been prepared on n-type GaN-coated sapphire substrates by radio frequency reactive magnetron sputtering at 100 °C followed by thermal annealing at 740 °C for 2 h. The ZnO/GaN heterojunction devices show a steady threshold switching (TS) characteristic. In addition, Mn-doped ZnO (MZO)/GaN heterojunction has been prepared and it shows lower threshold voltage and higher on/off ratio than those of ZnO/GaN heterojunction. The formation of TS characteristic may be attributed to trapping and detrapping of electrons in heterojunction device. Furthermore, the devices are investigated by the injection of photogenerated carriers, it is illustrated that the external carrier injection may affect the rate of the trapping of electrons and results in the decrease of the threshold voltage. [ABSTRACT FROM AUTHOR]

Even though the mesoporous-type perovskite solar cell (PSC) is known for high efficiency, its planar-type counterpart exhibits lower efficiency and hysteretic response. Herein, we report success in suppressing hysteresis and record efficiency for planar-type devices using EDTA-complexed tin oxide (SnO2) electron-transport layer. The Fermi level of EDTA-complexed SnO2 is better matched with the conduction band of perovskite, leading to high open-circuit voltage. Its electron mobility is about three times larger than that of the SnO2. The record power conversion efficiency of planar-type PSCs with EDTA-complexed SnO2 increases to 21.60% (certified at 21.52% by Newport) with negligible hysteresis. Meanwhile, the low-temperature processed EDTA-complexed SnO2 enables 18.28% efficiency for a flexible device. Moreover, the unsealed PSCs with EDTA-complexed SnO2 degrade only by 8% exposed in an ambient atmosphere after 2880 h, and only by 14% after 120 h under irradiation at 100 mW cm−2. The development of high efficiency planar-type perovskite solar cell has been lagging behind the mesoporous-type counterpart. Here Yang et al. modify the oxide based electron transporting layer with organic acid and obtain planar-type cells with high certified efficiency of 21.5% and decent stability. [ABSTRACT FROM AUTHOR]