The orthogonal structure of the widely used hole transporting material (HTM) 2,2',7,7'-tetrakis(N, N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD) imparts isotropic conductivity and excellent film-forming capability. However, inherently weak intra- and inter-molecular π-π interactions result in low intrinsic hole mobility. Herein, a novel HTM, termed FTPE-ST, with a twist conjugated dibenzo(g,p)chrysene core and coplanar 3,4-ethylenedioxythiophene (EDOT) as extended donor units, is designed to enhance π-π interactions, without compromising on solubility. The three-dimensional (3D) configuration provides the material multi-direction charge transport as well as excellent solubility even in 2-methylanisole, and its large conjugated backbone endows the HTM with a high hole mobility. Moreover, the sulfur donors in EDOT units coordinate with lead ions on the perovskite surface, leading to stronger interfacial interactions and the suppression of defects at the perovskite/HTM interface. As a result, perovskite solar cells (PSCs) employing FTPE-ST achieve a champion power conversion efficiency (PCE) of 25.21% with excellent long-time stability, one of the highest PCEs for non-spiro HTMs in n-i-p PSCs. In addition, the excellent film-forming capacity of the HTM enables the fabrication of FTPE-ST-based large-scale PSCs (1.0 cm2) and modules (29.0 cm2), which achieve PCEs of 24.21% (certificated 24.17%) and 21.27%, respectively.
Hot carrier solar cells could offer a solution to achieve high efficiency solar cells. Due to the hot-phonon bottleneck in perovskites, the hot carrier lifetime could reach hundreds of ps. Such that exploring perovskites could be a good way to promote hot carrier technology. With the incorporation of large organic cations, the hot carrier lifetime can be improved. By using ultrafast transient spectroscopy, the hot carrier relaxation and extraction kinetics are measured. From the transient kinetics, 2-phenyl-acetamidine cation based perovskites exhibit the highest initial carrier temperature, longest carrier relaxation, and slowest hot carrier relaxation. Such superior behavior could be attributed to reduced electron-phonon coupling induced by lattice strain, which is a result of the large organic cation and also a possible surface electronic state change. Our discovery exhibits the potential to use large organic cations for the use of hot carrier perovskite solar cells.
Perovskite photovoltaics, typically based on a solution-processed perovskite layer with a film thickness of a few hundred nanometres, have emerged as a leading thin-film photovoltaic technology. Nevertheless, many critical issues pose challenges to its commercialization progress, including industrial compatibility, stability, scalability and reliability. A thicker perovskite film on a scale of micrometres could mitigate these issues. However, the efficiencies of thick-film perovskite cells lag behind those with nanometre film thickness. With the mechanism remaining elusive, the community has long been under the impression that the limiting factor lies in the short carrier lifetime as a result of defects. Here, by constructing a perovskite system with extraordinarily long carrier lifetime, we rule out the restrictions of carrier lifetime on the device performance. Through this, we unveil the critical role of the ignored lattice strain in thick films. Our results provide insights into the factors limiting the performance of thick-film perovskite devices.
The black phase of formamidinium lead iodide (FAPbI3) perovskite shows huge promise as an efficient photovoltaic, but it is not favoured energetically at room temperature, meaning that the undesirable yellow phases are always present alongside it during crystallization1-4. This problem has made it difficult to formulate the fast crystallization process of perovskite and develop guidelines governing the formation of black-phase FAPbI3 (refs. 5,6). Here we use in situ monitoring of the perovskite crystallization process to report an oriented nucleation mechanism that can help to avoid the presence of undesirable phases and improve the performance of photovoltaic devices in different film-processing scenarios. The resulting device has a demonstrated power-conversion efficiency of 25.4% (certified 25.0%) and the module, which has an area of 27.83 cm2, has achieved an impressive certified aperture efficiency of 21.4%.
Perovskite crystal facets greatly impact the performance and stability of their corresponding photovoltaic devices. Compared to the (001) facet, the (011) facet yields better photoelectric properties, including higher conductivity and enhanced charge carrier mobility. Thus, achieving (011) facet-exposed films is a promising way to improve device performance. However, the growth of (011) facets is energetically unfavorable in FAPbI3 perovskites due to the influence of methylammonium chloride additive. Here, 1-butyl-4-methylpyridinium chloride ([4MBP]Cl) was used to expose (011) facets. The [4MBP]+ cation selectively decreases the surface energy of the (011) facet enabling the growth of the (011) plane. The [4MBP]+ cation causes the perovskite nuclei to rotate by 45° such that (011) crystal facets stack along the out-of-plane direction. The (011) facet has excellent charge transport properties and can achieve better-matched energy level alignment. In addition, [4MBP]Cl increases the activation energy barrier for ion migration, suppressing decomposition of the perovskite. As a result, a small-size device (0.06 cm2) and a module (29.0 cm2) based on exposure of the (011) facet achieved power conversion efficiencies of 25.24% and 21.12%, respectively.
Hole transport materials (HTMs) are a key component of perovskite solar cells (PSCs). The small molecular 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl)-amine-9,9'-spirobifluorene (spiro-OMeTAD, termed "Spiro") is the most successful HTM used in PSCs, but its versatility is imperfect. To improve its performance, we developed a novel spiro-type HTM (termed "DP") by substituting four anisole units on Spiro with 4-methoxybiphenyl moieties. By extending the π-conjugation of Spiro in this way, the HOMO level of the HTM matches well with the perovskite valence band, enhancing hole mobility and increasing the glass transition temperature. DP-based PSC achieves high power conversion efficiencies (PCEs) of 25.24 % for small-area (0.06â cm2 ) devices and 21.86 % for modules (designated area of 27.56â cm2 ), along with the certified efficiency of 21.78 % on a designated area of 27.86â cm2 . The encapsulated DP-based devices maintain 95.1 % of the initial performance under ISOS-L-1 conditions after 2560â hours and 87 % at the ISOS-L-3 conditions over 600â hours.
As the field of soft robotics advances, full autonomy becomes highly sought after, especially if robot motion can be powered by environmental energy. This would present a self-sustained approach in terms of both energy supply and motion control. Now, autonomous movement can be realized by leveraging out-of-equilibrium oscillatory motion of stimuli-responsive polymers under a constant light source. It would be more advantageous if environmental energy could be scavenged to power robots. However, generating oscillation becomes challenging under the limited power density of available environmental energy sources. Here, we developed fully autonomous soft robots with self-sustainability based on self-excited oscillation. Aided by modeling, we have successfully reduced the required input power density to around one-Sun level through a liquid crystal elastomer (LCE)-based bilayer structure. The autonomous motion of the low-intensity LCE/elastomer bilayer oscillator "LiLBot" under low energy supply was achieved by high photothermal conversion, low modulus, and high material responsiveness simultaneously. The LiLBot features tunable peak-to-peak amplitudes from 4 to 72 degrees and frequencies from 0.3 to 11 hertz. The oscillation approach offers a strategy for designing autonomous, untethered, and sustainable small-scale soft robots, such as a sailboat, walker, roller, and synchronized flapping wings.
Thiol-gold (S-Au) chemistry has been widely used in coating and functionalizing gold surfaces because it is robust and highly efficient. However, recent studies have shown that the S-Au-based self-assembled monolayers can lead to significant instability under external mechanical loading (e.g., in a swelled polymer film). Such instability limits further applications of S-Au chemistry-based functional materials. Here, we report a surface-modifying procedure based on a parallel covalent strategy. By employing dendritic macromolecules as a "middle layer" between the gold surface and polymer, the interfacial connecting strength increased by at least 350% as revealed by atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS). The ultimate cleavage structure is confirmed to be an amide bond by control SMFS experiments, fluorescent microscopy, and dynamic force spectroscopy. This study/concept paves the way to prepare stable stimuli-responsive polymer brushes on solid surfaces and study mechanophores with high force stability.
Cations with suitable sizes to occupy an interstitial site of perovskite crystals have been widely used to inhibit ion migration and promote the performance and stability of perovskite optoelectronics. However, such interstitial doping inevitably leads to lattice microstrain that impairs the long-range ordering and stability of the crystals, causing a sacrificial trade-off. Here, we unravel the evident influence of the valence states of the interstitial cations on their efficacy to suppress the ion migration. Incorporation of a trivalent neodymium cation (Nd3+) effectively mitigates the ion migration in the perovskite lattice with a reduced dosage (0.08%) compared to a widely used monovalent cation dopant (Na+, 0.45%). The photovoltaic performances and operational stability of the prototypical perovskite solar cells are enhanced with a trace amount of Nd3+ doping while minimizing the sacrificial trade-off.
As classic shape memory polymers featuring shape reconfiguration of temporary state, covalent adaptable networks containing reversible bonds can enable permanent-state reconfigurability through topological rearrangement via dynamic bond exchange. Yet, such an attractive dual shape programmability is limited by the actuation mode of direct heat transfer and poor mechanical properties, restricting its control precision and functionality. Herein, we presented a method to create nanocomposites with photomodulated dual shape programmability and remarkable mechanical properties leading the fields of covalent adaptable networks. MXene, whose photothermal efficiency was revealed to be regulated by the etching method and delamination, was introduced into polyurethane networks. Upon adjusting the light intensity, the dual shape programmability of both permanent and temporary states could be accomplished, which exhibited potential in information recognition, photowriting paper, etc. Furthermore, owing to the dynamic transcarbamoylation at elevated temperatures, such a phototriggered dual shape programmability could be maintained after the self-healing and reprocessing.
Nanocomposites , Polymers , Polymers/chemistry , Polyurethanes , Light , Hot Temperature
Combining the high stability under UV light of the wide bandgap (WBG) perovskite solar cells (pero-SCs) and the broad near-infrared absorption spectra of the narrow bandgap (NBG) organic solar cells (OSCs), the perovskite/organic tandem solar cells (TSCs) with the WBG pero-SC as front cell and the NBG OSC as rear cell have attracted attention . However, the photovoltaic performance of the perovskite/organic TSCs needs to be further improved. Herein, nonradiative charge recombination loss is reduced through bulk defect passivation in the WBG pero-SC front subcell and broadening the range of absorption spectra of the NBG OSC rear cell. For the WBG pero-SCs, an organic cation chloro-formamidinium is introduced into FA0.6 MA0.4 Pb(I0.6 Br0.4 )3 to passivate the bulk defects in the perovskite film and the WBG pero-SC displays high open-circuit voltage of 1.25 V and high fill factor of 83.0%. For the NBG OSCs, a new infrared-absorbing organic small molecule acceptor BTPV-4Cl-eC9 is designed and synthesized. Then, a monolithic perovskite/organic TSC is fabricated with the WBG pero-SC as the front cell and the NBG OSC as the rear cell, and the TSC demonstrates high power conversion efficiency up to 22.0%. The results indicate that the perovskite/organic TSC is promising for future commercialization.
OBJECTIVE: To explore clinical effect of internal and external fixation combined with second-stage perforator fiap for the treatment of ankle fracture dislocation of Gustilo-Anderson types â ¢B and â ¢C. METHODS: From May 2014 to July 2017, 20 patients with Gustilo-Anderson types â ¢B and â ¢C ankle fracture dislocation were treated with internal and external fixation combined with second-stage perforator fiap, including 14 males and 6 females, aged from 18 to 58 years old with an average of (39.0±9.7) years old;17 patients were type â ¢B and 3 patients were type â ¢C according to Gustilo-Anderson classification;4 patients were type A, 7 patients were type B, and 9 patients were type C according to AO classification. The size of wound ranged from 4 cm×3 cm to 20 cm×9 cm. Second-stage perforator flap, 11 patients were performed with posterior tibial artery perforator flap, 5 patients were performed with fibular artery perforator flap, 1 patient was performed with anterior ankle flap, and 3 patients were performed with posterior tibial artery perforator flap combined with fibular artery perforator flap. Postoperative wound healing, flap survival and fracture healing were observed, AOFAS score was used to evaluate at the latest follow up. RESULTS: All limbs were preserved successfully without amputation. Nine patients occurred superficial infection without deep infection and osteomyelitis occurring. The flaps of 19 patients survived. All patients were followed up for 6 to 18 months with an average of (12.0±2.9) months. The flaps healed well without sinus tract, bone exposure and bone disunion occurring. Fracture healing time ranged from 4 to 10 months with an average of (6.6±1.7) months. PostoperativeAOFAS score was 76.7± 16.4, among which 4 patients got excellent result, 11 patients good, 3 patients fair, and 2 poor. CONCLUSION: Internal and external fixation combined with second stage perforator fiap for the treatment of ankle fracture dislocation of Gustilo-Anderson types â ¢B and â ¢C could effectively close the wound, improve fracture healing and restore appearance and function of limbs to the maximum.
Fracture Dislocation , Perforator Flap , Plastic Surgery Procedures , Soft Tissue Injuries/surgery , Adolescent , Adult , Ankle , Female , Fracture Fixation, Internal , Humans , Male , Middle Aged , Skin Transplantation , Treatment Outcome , Young Adult
Considering the high incidence of postoperative complications of open fracture, management of this injury is an intractable challenge for orthopaedist, and surgical site infection (SSI) is the devastate one. Screening for high-risk patients and target them with appropriate interventions is important in clinical practice. The aim of this study was to identify modifiable factors that were associated with SSI following operative treatment of open fractures. This retrospective, multicentre study was conducted at three hospitals. A total of 2692 patients with complete data were recruited between June 2015 and July 2018. Demographic characteristics, operation relative variables, additional comorbidities, and biochemical indexes were extracted and analysed. Receiver operating characteristic analysis was performed to detect the optimum cut-off value for some variables. Univariate and multivariate logistic analysis models were performed, respectively, to identify the independent risk factors of SSI. The overall incidence of SSI was 18.6%, with 17.0% and 1.6% for superficial and deep infection, respectively. Results of univariate and multivariate analyses showed the following: fracture type, surgical duration > 122 minutes, anaesthesia time > 130 minutes, intraoperative body temperature < 36.4°C, blood glucose (GLU) > 100 mg/dL, blood platelet (PLT) < 288 × 109 , and white blood cells (WBC) > 9.4 × 109 were independent risk factors of postoperative wound infection following operative treatment of open fractures. Six modifiable factors such as surgical duration > 122 minutes, anaesthesia time > 130 minutes, intraoperative body temperature < 36.4°C, GLU > 100 mg/dL, PLT < 288 × 109, and WBC > 9.4 × 109 play an important role in the prevention of SSI, and these factors should be optimized perioperatively.
Fracture Fixation/adverse effects , Fractures, Open/surgery , Surgical Wound Infection/epidemiology , Adolescent , Adult , Aged , Aged, 80 and over , Blood Cell Count , Blood Glucose , Body Temperature , Female , Humans , Incidence , Male , Middle Aged , Operative Time , Prognosis , ROC Curve , Retrospective Studies , Risk Factors , Young Adult
Thickness controllable porous polymer nanofilm with superior gas storage capacity has gradually emerged as promising adsorbents for capture of CO2, due to extremely high surface area and micro-scale pore. In this work, we have developed a novel and facile strategy to fabricate thickness controllable two or three dimensional ordered porous nanofilm based on poly(styrene-butyl acrylate), in combination with covalently layer by layer (LBL) self-assemble process and hypercrosslinked post-treatment. Abundant microporous structures and a small number of mesoporous structures are formed in hypercorsslinked nanofilm and corresponding surface area derived from Brunauer-Emmett-Teller method (BET) were determined to be 605.7 m2/g. The capacity of CO2 capture was also measured, which reach up to 53.6 wt% (12.2 mmol/g) at 273 K/1 bar, which is comparable to highest record. We have found that all the as prepared nanofilm with different thickness exhibited apparently enhanced micro- and meso-porosity after hypercrosslinking. Moreover, with the increase of thickness of nanofilm, the adsorption capacity decreases gradually, as well as the CO2 adsorption capacity. An excellent recycling capacity for CO2 capture have also found for this porous polymer nanofilm via repetitive adsorption-desorption assay. Our work confirmed that thickness controllable porous polymer nanofilm with superior CO2 capture capacity can be fabricated by a very simple strategy which can meet the challenges of the current CO2 capture and storage technology.
Formamidinium (FA) lead halide (α-FAPbI3) perovskites are promising materials for photovoltaic applications because of their excellent light harvesting capability (absorption edge 840 nm) and long carrier diffusion length. However, it is extremely difficult to prepare a pure α-FAPbI3 phase because of its easy transformation into a nondesirable δ-FAPbI3 phase. In the present study, a "perovskite" template (MAPbI3-FAI-PbI2-DMSO) structure is used to avoid and suppress the formation of δ-FAPbI3 phases. The perovskite structure is formed via postdeposition involving the treatment of colloidal MAI-PbI2-DMSO film with FAI before annealing. In situ X-ray diffraction in vacuum shows no detectable δ-FAPbI3 phase during the whole synthesis process when the sample is annealed from 100 to 180 °C. This method is found to reduce defects at grain boundaries and enhance the film quality as determined by means of photoluminescence mapping and Kelvin probe force microscopy. The perovskite solar cells (PSCs) fabricated by this method demonstrate a much-enhanced short-circuit current density ( J sc) of 24.99 mA cm-2 and a power conversion efficiency (PCE) of 21.24%, which is the highest efficiency reported for pure FAPbI3, with great stability under 800 h of thermal ageing and 500 h of light soaking in nitrogen.
Nontoxic and stable materials are one of the necessities for commercialization of solar devices. However, most lead-free absorbers have limited light absorption range as well as poor morphology. In this work, a vertically oriented BiI3 template induced by Li-bis(trifluoromethanesulfonyl)imide dopant is intimately integrated with a light-absorbing polymer to form an organic-inorganic BiI3/polymer heterojunction absorber in solar cells. Compared with the dopant-free BiI3/polymer, the broadened light absorption of the doped BiI3/polymer enhances the external quantum efficiency (EQE) of the device beyond 500 nm as well as extends the EQE edge from 650 to 750 nm, which significantly increases the short-circuit current (Jsc) of the device from 1.3 to 3.7 mA cm-2. The polymer top layer is further optimized to improve charge extraction, which achieved the highest Jsc recorded (7.8 mA cm-2) for BiI3-based solar cells and an efficiency of 1.03%. Moreover, the encapsulated device shows no degradation after storing in ambient conditions for nearly 2 years.
OBJECTIVE: To investigate the effectiveness of dorsalis pedis flap series-parallel big toe nail composite tissue flap in the repairment of hand skin of degloving injury with tumb defect. METHODS: Between March 2009 and June 2013, 8 cases of hand degloving injury with thumb defect caused by machine twisting were treated. There were 7 males and 1 female with the mean age of 36 years (range, 26-48 years). Injury located at the left hand in 3 cases and at the right hand in 5 cases. The time from injury to hospitalization was 1.5-4.0 hours (mean, 2.5 hours). The defect area was 8 cm x 6 cm to 15 cm x 1 cm. The thumb defect was rated as degree I in 5 cases and as degree II in 3 cases. The contralateral dorsal skin flap (9 cm x 7 cm to 10 cm x 8 cm) combined with ipsilateral big toe nail composite tissue flap (2.5 cm x 1.8 cm to 3.0 cm x 2.0 cm) was used, including 3 parallel anastomosis flaps and 5 series anastomosis flaps. The donor site of the dorsal flap was repaired with thick skin grafts, the stumps wound was covered with tongue flap at the shank side of big toe. RESULTS: Vascular crisis occurred in 1 big toe nail composite tissue flap, margin necrosis occurred in 2 dorsalis pedis flap; the other flaps survived, and primary healing of wound was obtained. The grafted skin at dorsal donor site all survived, skin of hallux toe stump had no necrosis. Eight cases were followed up 4-20 months (mean, 15.5 months). All flaps had soft texture and satisfactory appearance; the cutaneous sensory recovery time was 4-7 months (mean, 5 months). At 4 months after operation, the two-point discrimination of the thumb pulp was 8-10 mm (mean, 9 mm), and the two-point discrimination of dorsal skin flap was 7-9 mm (mean, 8.5 mm). According to Society of Hand Surgery standard for the evaluation of upper part of the function, the results were excellent in 4 cases, good in 3 cases, and fair in 1 case. The donor foot had normal function. CONCLUSION: Dorsalis pedis flap series-parallel big toe nail composite tissue flap is an ideal way to repair hand skin defect, and reconstructs the thumb, which has many advantages, including simple surgical procedure, no limitation to recipient site, soft texture, satisfactory appearance and function of reconstructing thumb, and small donor foot loss.
Amputation, Traumatic/surgery , Finger Injuries/surgery , Skin Transplantation/methods , Surgical Flaps/innervation , Thumb/abnormalities , Thumb/surgery , Adult , Amputation Stumps , Female , Hallux , Humans , Male , Middle Aged , Nails , Plastic Surgery Procedures/methods , Sensation , Skin/injuries , Soft Tissue Injuries/surgery , Surgical Flaps/blood supply , Tendons , Thumb/blood supply , Thumb/innervation , Treatment Outcome , Wound Healing , Young Adult
OBJECTIVE: To investigate the therapeutic effect of modified side-to-end lymphaticovenular anastomosis in the treatment of post-mastectomy upper limb lymphedema. METHODS: Between May 2010 and May 2011, 11 female patients with post-mastectomy upper limb lymphedema underwent a modified side-to-end lymphaticovenular anastomosis. The average age was 49.5 years (range, 38-55 years). Lymphedema occurred at 7-30 months (mean, 18.3 months) after resection of breast cancer, with an average disease duration of 25.5 months (range, 10-38 months). The left upper limb was involved in 5 cases and the right upper limb in 6 cases. In accordance with difference value between health and affected sides criteria, 5 cases were rated as moderate, and 6 cases as severe. RESULTS: Modified side-to-end lymphaticovenular anastomosis was successfully completed in all patients. Primary healing of incision was obtained in the other patients except 1 case of delayed healing. All patients were followed up for an average of 38.4 months (range, 36-40 months). Limb pain and swelling were relieved; no episodic attack or recurrence was observed. The circumference of affected upper arm was significantly decreased from preoperative (33.9 ± 3.7) cm to postoperative (31.0 ± 3.5) cm at 6 months and (30.9 ± 3.5) cm at 36 months (P < 0.05), but no significant difference was found between at 3 and 6 months (P > 0.05); the circumference of affected forearm was significantly decreased from preoperative (30.1 ± 3.6) cm to postoperative (27.8 ± 3.4) cm at 6 months and (27.7 ± 3.3) cm at 36 months (P < 0.05), but no significant difference was shown between at 6 and 36 months (P > 0.05). According to Campis evaluation standard to assess efficacy, the results were excellent in 3 cases, good in 6 cases, and improved in 2 cases CONCLUSIO: n Using modified side-to-end lymphaticovenular anastomosis may be effective in the treatment of upper limb lymphedema after mastectomy.
Arm/surgery , Breast Neoplasms/surgery , Lymphatic Vessels/surgery , Lymphedema/etiology , Lymphedema/surgery , Mastectomy/adverse effects , Adult , Anastomosis, Surgical/methods , Arm/blood supply , Female , Humans , Lymphatic Vessels/blood supply , Lymphedema/physiopathology , Microsurgery , Middle Aged , Neoplasm Recurrence, Local , Postoperative Complications , Treatment Outcome , Vascular Surgical Procedures
