Realizing high-performance organic solar cells through precise control of HOMO driving force based on ternary alloy strategy

A good deal of studies have proven that effective exciton dissociation and fast hole transport can operate efficiently in non-fullerene organic photovoltaics(OPVs)despite nearly zero driving force.Even so,whether such a phenomenon is universal and how small the driving force can realize the best photovoltaic performance still require a thorough understanding.Herein,despite the zero driving force based on PM6:F8IC system,a maximum short-circuit current(J_(sc))of 23.0 mA/cm^(2) and high power conversion efficiency(PCE)of 12.2%can still be achieved.Due to the continuously adjustable energy levels can be realized in organic semiconducting alloys including F8IC:IT-4F and F8IC:Y6,the suitable third components can play the role of energy level regulator.Therefore,the HOMO energy level offset(DEHOMO(D A))from zero to 0.07 and 0.06 eV is accomplished in the optimized IT-4F and Y6 ternary devices.Consequently,both ternary devices achieved substantially increased PCE of 13.8%and Jsc of 24.4 and 25.2 mA/cm^(2),respectively.Besides,pseudo-planar heterojunction(PPHJ)devices based on alloyed acceptors through sequential spin-coating method further improve the photovoltaic performance.Our work puts forward the concept of energy level regulator and prove that the ternary alloy strategy has unique advantages and huge research potential in continuously adjusting the driving force.

Metal-organic frameworks derived transition metal phosphides for electrocatalytic water splitting

It is critical to synthesize high-efficiency electrocatalysts to boost the performance of water splitting to meet the requirements of industrial applications. Metal-organic frameworks(MOFs) can function as ideal molecular platforms for the design of highly reactive transition metal phosphides(TMPs), a kind of candidates for high-efficiently electrocatalytic water splitting. The intrinsic activity of the electrocatalysts can be greatly improved via modulating the electronic structure of the catalytic center through the MOF precursors/templates. Moreover, the carbon layer converted in-situ by the organic ligands can not only protect the TMPs from being degraded in the harsh electrochemical environments, but also avoid agglomeration of the catalysts, thereby promoting their activities and stabilities. Furthermore,heteroatom-containing ligands can incorporate N, S or P, etc. atoms into the carbon matrixes after conversion, regulating the coordination microenvironments of the active centers as well as their electronic structures. In this review, we first summarized the latest developments in MOF-derived TMPs by the unique advantages in metal, organic ligand, and morphology regulations for electrocatalytic water splitting. Secondly, we concluded the critical scientific issues currently facing for designing state-of-the-art TMP-based electrocatalysts. Finally, we presented an outlook on this research area, encompassing electrocatalyst construction, catalytic mechanism research, etc.

Non-conjugated terpolymer acceptors for highly efficient and stable lager-area all-polymer solar cells

All-polymer solar cells(all-PSCs)have made significant progress recently,but few studies have been conducted to investigate the lab-to-manufacturing translation from the spin-coating method to the printing process.Here,the random copolymerization method and non-conjugated backbone approach are integrated to manipulate the morphology and photoelectric properties of the active layer for large-area printed all-PSCs.A series of non-conjugated terpolymer acceptors PYSe-TC_(6)T(x)(x=5,10,and 20,refers to the molar ratio of TC_(6)T unit)are developed by covalently introducing non-conjugated unit TC_(6)T into the PYSe host bipolymer by random copolymerization.The spin-coated PYSe-TC_(6)T(10)-based all-PSC demonstrates the best power conversion efficiency(PCE)of 13.54%,superior to the PYSe-based one(12.45%).More intriguingly,morphological studies reveal that a combination of the random polymerization and non-conjugated backbone strategy can effectively prevent the active layer from overaggregation and improve the film quality during the printing process,thereby minimizing the efficiency and technology gap between spin-coated small-area devices and blade-coated large-area devices.By directly using the same preparation condition of spin-coating,the blade-coated small-area(0.04 cm^(2))delivers a PCE of 12.83%and the large-area(1.21 cm^(2))device achieves a PCE of 11.96%with a small PCE loss.Both PCE value and PCE loss are one of the most outstanding performances of the bladecoated all-PSCs.These findings reveal that a combination of the non-conjugated flexible backbone with random copolymerization to develop non-conjugated terpolymers is an attractive design concept to smoothly realize the lab-to-manufacturing translation.

Molecular crowding agents engineered to make bioinspired electrolytes for high-voltage aqueous supercapacitors

The development of low-cost and eco-friendly aqueous electrolytes with a wide voltage window is the key to achieving safe high energy density supercapacitors(SCs).In this work,a molecular crowding electrolyte is prepared by simulating the crowded environment in living cells.Ion transport in the molecular crowding electrolyte can be effectively improved via reducing the molecular weight of the crowding agent,polyethylene glycol(PEG).The results show that PEG with a molecular weight of 200(PEG200)can significantly improve ionic conductivity while maintaining a wide voltage window.These advantages enable commercial activated carbon-based SCs to work at 2.5 V with high energy density,outstanding rate performance and good stability for more than 10,000 cycles.On this basis,three series of molecular crowding electrolytes using sodium perchlorate,lithium perchlorate,and sodium trifluoromethanesulfonate as salts are developed,demonstrating the versatility of PEG200 for wide-voltage aqueous electrolytes.

Bending-stability Interfacial Layer as Dual Electron Transport Layer for Flexible Organic Photovoltaics

The flexibility of organic photovoltaics(OPVs)has attracted worldwide attention in recent years.To realize the bending-stability of OPVs,it is necessary to put forward the bending-stability of interfacial layer.A novel bendable composite is explored and successfully applied as an electron transport layer(ETL)for fully-flexible OPVs.We incorporated poly(vinylpyrrolidone)(PVP)into conjugated electrolytes(CPE)to composite a bendable ETL for high-performance OPVs devices.Fortunately,the devices based on PVP-modified CPE exhibited better device performances and more excellent mechanical properties of bendability.The fullerene-free OPVs based on PM6:IT-4 F with CPE@PVP as ETLs yield the best power conversion efficiency(PCE)of 13.42%.Moreover,a satisfying efficiency of 12.59%has been obtained for the fully-flexible OPVs.As far as we know,this is one of the highest PCE for fully-flexible OPV based PM6:IT-4 F system.More importantly,the flexible OPVs devices can retain more than 80%of its initial efficiency after 5000 bending cycles.Furthermore,among various curvature radii,the mechanical properties of the device based on CPE@PVP are superior to those of the device based on bare CPE as ETL.These findings indicate that the functional flexibility of CPE as a cathode interfacial layer is an effective strategy to fabricate high-performance flexible devices in the near future.

Robust hydrogen production from HCOOH over amino-modified KIT-6-confined Pd Ir alloy nanoparticles

Formic acid (FA), which can be produced via CO_(2) reduction and biomass conversion, has received extensive interest as a convenient and safe hydrogen carrier due to its wide range of sources, renewable, high hydrogen content (4.4 wt%), and convenient storage/transportation. Designing highly efficient catalysts is the main challenge to realize the hydrogen production from FA. In this work, well-dispersed and electron-rich PdIr alloy nanoparticles with a size of 1.8 nm are confined in amino-modified 3D mesoporous silica KIT-6 and applied as a highly efficient catalyst for robust hydrogen production from FA at ambient temperature. Small PdIr alloy nanoparticles confined by amino-modified KIT-6 (PdIr/KIT-6-NH_(2)) lead to better catalytic activity compared to that of Pd/KIT-6-NH_(2) and PdIr confined by bare KIT-6, achieving a high turnover frequency (TOF) value of 3533 h-1 at ambient temperature (303 K), 100% H_(2) selectivity and conversion toward the dehydrogenation of FA, which is comparable to the best heterogeneous catalysts ever reported. The high catalytic activity of PdIr/KIT-6-NH_(2) can be attributed to the synergistic effect between Pd and Ir, strong interaction between PdIr and KIT-6-NH_(2), as well as the amino-groups of KIT-6-NH_(2) which can act as a proton scavenger to promote the breaking of O-H bond of formic acid.

Printable and stable all-polymer solar cells based on non-conjugated polymer acceptors with excellent mechanical robustness

All-polymer solar cells(all-PSCs)trigger enormous commercial applications,and great progress has been made in recent years.However,from small-area devices to large-area modules,the poor adaption of the materials for printing methods and the large efficiency loss are still great challenges.Herein,three novel non-conjugated polymer acceptors(PTH-Y,PTClm-Yand PTClo-Y)are developed for all-PSCs.It can be found that non-conjugated polymer acceptors can effectively minimize the technique and efficiency gaps between small-area spin-coating and large-area blade-printing method,which can facilitate the preparation of large-area flexible device.By directly inheriting the spin-coating condition,the blade-coating processed device based on PTCloY achieves an impressive power conversion efficiency(PCE)of 12.42%,comparable to the spin-coating processed one(12.74%).Such a non-conjugated polymer system also can well tolerate large-scale preparation and flexible substrate.Notable PCE of 11.94%for large-area rigid device and 11.56%for large-area flexible device are obtained,which is the highest value for large-area flexible all-PSCs fabricated by blade-coating.In addition,the non-conjugated PTClo-Y-based devices show excellent thermal stability and mechanical robustness.These results demonstrate that the non-conjugated polymer acceptors are potential candidates for the fabrication of highly-efficient,large-area and robust flexible all-PSCs by printing methods.

2022 roadmap on hydrogen energy from production to utilizations

Hydrogen has been always the hot topic,which drives a lot of researchers to study and explore hydrogenrelated projects and fields.The first subfield is hydrogen production with green and cost-effective means.Some methods have been intensively used for high-efficient hydrogen production,i.e.,catalytic chemical hydrogen generation,electrocatalytic hydrogen evolution,photocatalytic hydrogen evolution,photo-electrocatalytic hydrogen evolution.Most of them are driven by various catalysts.Moreover,the hydrogen storage is also an important question,which is also a present research hot topic,although the history is long with several decades.Hydrogen fuel cells have also obtained great attention due to the zero emissions.The related research mainly focuses on the cell systems and electrocatalysts used.Under this background,we invite some excellent research groups to write this progress on hydrogen from production to utilizations.Finally,we believe that this roadmap on hydrogen can give some useful guidance in future research.

钙钛矿前驱体溶液中的胶体化学

As an outstanding energy-harvesting technology,perovskite solar cells(PSCs)have gained much attention due to the excellent photoelectric performance.The performance of PSCs has been promoted to achieve breakthroughs repeatedly with composition regulation,interface engineering,additive strategy and so on.To date,the certification efficiency of PSCs has reached 25.5%with a great commercial feasibility(https://www.nrel.gov/pv/cell-efficiency.html).