Efficient and photostable CsPbI_(2) Br solar cells realized by adding PMMA

Organic–inorganic hybrid perovskite materials demonstrate promising applications in high-efficiency perovskite solar cells (PSCs) with a certified power conversion efficiency(PCE) of 25.5%(https://www.nrel.gov/pv/cell-efficiency.html).

When insulating polymers meet conjugated polymers:the noncovalent bonding does matter

Insulating polymers are characterized by a predominantlyσ-covalent structure,which localize electrons in the atoms and exhibit dielectricity.Insulating polymers typically adopt a more linear and extended conformation,as the repeating units are connected by single covalent bonds,resulting in a relatively straight and extended chain structure.For most insulating polymers,the contour length(L_(c))is significantly larger than their persistence length(Lp)due to the rotation of C−C single bonds(Fig.1(a)).Consequently,this leads to a flexible,random-coil chain conformation.This structural feature contributes to the great mechanical durability and resistance to crack initiation during stretching or bending processes.In contrast,conjugated polymers possess aπ-conjugated molecular structure,allowing electron mobility along the main chain,called delocalization,which imparts semiconducting properties[1,2].The presence of rigid,alternating single and multiple bonds results in comparable Lc and Lp,thereby yielding a stiff or semi-flexible conformation(Fig.1(b))[3,4].As a consequence,most conjugated polymers are prone to fracture under low strain levels(<10%)[5−7].

Regulation of the quantum barrier and carrier transport toward high-efficiency quasi-2D Dion-Jacobson tin perovskite solar cells

Quasi-2D Dion-Jacobson(DJ)tin halide perovskite has attracted much attention due to its elimination of Van der Waals gap and enhanced environmental stability.However,the bulky organic spacers usually form a natural quantum well structure,which brings a large quantum barrier and poor film quality,further limiting the carrier transport and device performance.Here,we designed three organic spacers with different chain lengths(ethylenediamine(EDA),1,3-propanediamine(PDA),and 1,4-butanediamine(BDA))to investigate the quantum barrier dependence.Theoretical and experimental characterizations indicate that EDA with short chain can reduce the lattice distortion and dielectric confinement effect,which is beneficial to the effective dissociation of excitons and the inhibition of trap-free non-radiative relaxation.In addition,EDA cation shows strong interaction with the inorganic octahedron,realizing large aggregates in precursor solution and high-quality films with improved structural stability.Furthermore,femtosecond transient absorption proves that EDA cations can also weaken the formation of small n-phases with large quantum barrier to achieve effective carrier transport between different nphases.Finally,the quasi-2D DJ(EDA)FA_(9)Sn_(10)I_(31)solar cells achieves a 7.07%power conversion efficiency with good environment stability.Therefore,this work sheds light on the regulation of the quantum barrier and carrier transport through the chain length of organic spacer for qua si-2D DJ lead-free perovskites.

Organic solar cells with D18 or derivatives offer efficiency over 19%

In recent years,organic solar cells(OSCs)have garnered significant attention due to their distinctive attributes,such as flexibility,lightweight,and solution processing,which position them as alternatives for next-generation solar technologies[1−5].Thanks to breakthroughs in materials development,the power conversion efficiency(PCE)for single-junction OSCs has already surpassed 19%[6−13].The development of photoactive materials is pivotal in enhancing the PCEs,and several reviews have provided insights into materials design[14−18].Herein,we highlight single-junction OSCs based on D18 and its derivatives[19,20].

2D black arsenic phosphorous

Since the successful exfoliation of graphene in 2014,twodimensional(2D)materials have explosively increased in the past few years[1].2D pnictogen materials with intriguing properties beyond graphene are gradually coming into eyesight,such as black phosphorous(BP)[2],arsenene[3],antimonene[4],bismuthine[5],etc.BP is a star material in 2D materials.

Effect of drying methods on perovskite films and solar cells

The high efficiency,solution processibility,and flexibility of perovskite solar cells make them promising candidates for the photovoltaic industry[1−8].The deposition method is one of the most critical factors that affect the performance of perovskite films.Various deposition methods have been developed to make perovskite films,including spin-coating,slotdie coating.

Engineering fibrillar morphology for highly efficient organic solar cells

The power conversion efficiency(PCE)for single-junction organic solar cells(OSCs),wherein the photoactive layer is a typical bulk-heterojunction containing donor and acceptor materials,has surpassed 19%[1−4].The advance is ascribed to the development of Y-series non-fullerene acceptors(NFAs)[5,6]and polymer donors[7−13],and the refined control of the blend film morphology.

Chemical vapor deposition for perovskite solar cells and modules

Metal halide perovskites are promising materials for solar cells because of high power conversion efficiency(PCE),tun-able bandgap,high defect tolerance,long carrier diffusion length,and low-cost fabrication[1-7].The PCE for perovskite solar cells(PSCs)reaches 26.14%for single-junction cells,29.1%for perovskite/perovskite tandem cells and 33.9%for perovskite/silicon tandem cells,being comparable to that for silicon and other thin-film solar cells[8-10].Perovskite solar cells have been made by solution methods including spin-coat-ing,blade coating and printing[11,12].

25%-Efficiency flexible perovskite solar cells via controllable growth of SnO_(2)

High power conversion efficiency(PCE)flexible perovskite solar cells(FPSCs)are highly desired power sources for aerospace crafts and flexible electronics.However,their PCEs still lag far behind their rigid counterparts.Herein,we report a high PCE FPSC by controllable growth of a SnO_(2)electron transport layer through constant pH chemical bath deposition(CBD).The application of SnSO_(4)as tin source enables us to perform CBD without strong acid,which in turn makes it applicable to acid-sensitive flexible indium tin oxide.Furthermore,a mild and controllable growth environment leads to uniform particle growth and dense SnO_(2)deposition with full coverage and reproducibility,resulting in a record PCE of up to 25.09%(certified 24.90%)for FPSCs to date.The as-fabricated FPSCs exhibited high durability,maintaining over 90% of their initial PCE after 10000 bending cycles.

Machine learning assisted prediction for hydrogen production of advanced photovoltaic technologies

The photovoltaic(PV)water electrolysis method currently stands as the most promising approach for green hydrogen production.The rapid iteration of photovoltaic technologies has significantly affected on the technical and economic evaluation for photovoltaic hydrogen production.In this work,the photovoltaic hydrogen production of three most advanced silicon photovoltaic technologies is systematically compared for the first time under the climatic conditions of the Kucha region.All-weather stable hydrogen production control system with optimal charging and discharging strategies is constructed to realize stable and efficient hydrogen energy production.Seven machine learning(ML)algorithms are used to forecast the performance in power generation and hydrogen production of a 100 MW photovoltaic hydrogen production and energy storage(PH-S)system throughout its operational life.The long short-term memory(LSTM)algorithm exhibits the best performance,achieving mean absolute error(MAE)of 0.0415,root mean square error(RMSE)of 0.0891,and coefficient of determination(R2)of 0.8402.In terms of cost-effectiveness,heterojunction with intrinsic thin layer(HJT)PV technology achieves the lowest levelized cost of electricity(LCOE)and hydrogen(LCOH)at 0.025$/kWh and 6.95$/kg,respectively.According to the sensitivity analysis,when the cost of proton exchange membrane electrolysis(PEMEC)reduced 50%,the LCOH for PH-S system decreased 21.40%.This study provides valuable insights for the practical implementation of large-scale photovoltaic hydrogen production and cost reduction in PH-S systems.

A review from fundamental research to device applications for graphene-based thermal rectifier

Thermal rectification(TR)is a phenomenon akin to electrical rectification.It has a high thermal conductivity(k)in one direction,enabling efficient heat dissipation,as well as a low k in the opposite direction,impeding heat influx.With the rapid development of nanotechnology in recent years,the active control and regulation of heat conduction on the nanoscale has become a critical mission.Graphene,a prominent two-dimensional(2D)material,is highly regarded for its exceptional thermal transport characteristics.There have been studies and achievements both theoretically and experimentally since its discovery.In this review,we establish a bridge between fundamental research and application studies for graphene-based thermal rectifier as follows.Firstly,we summarize the established 2D heat conduction theories and low-dimensional simulation methods.Secondly,we review the progress of experimental techniques and device structures based on 2D theories for graphene-based thermal rectifier.Then,we discuss several applications of thermal rectifier,including thermal logic circuits and thermoelectric power generation system.Finally,we present the potential applications of graphene-based thermal rectifiers previously unexplored,such as microelectronic thermal management and thermal decoupling for flexible equipment.We hope that advancements in morphology and fabrication techniques will lead to widespread use of graphene-based thermal rectifiers in various thermal systems to solve diverse thermal management problems in the near future.

D18, an eximious solar polymer!

Organic solar cell(OSC)is a promising photovoltaic technology with great commercialization potential due to the advantages like solution-processing,roll-to-roll fabrication,lightweight,flexibility,and semitransparency[1−7].Conjugated polymer donors are key materials for OSCs[8].

18.69% PCE from organic solar cells

The exquisite design and persistent development of fused-ring-acceptor-unit-based copolymer donors and Yseries nonfullerene acceptors(NFAs)have pushed the power conversion efficiencies(PCEs)for organic solar cells onto the18%level[1-21].Our group invented copolymer donors D18 and D18-Cl[2,3].D18:Y6,D18-Cl:N3 and D18:N3 solar cells have delivered outstanding PCEs of 18.22%,18.13%and18.56%,respectively[2-4].Ternary solar cells based on a polymer donor,a NFA and a fullerene acceptor show great potential since they combine good light-harvesting capability of NFA and good electron-mobility of fullerene[5].

Advances in the Application of Perovskite Materials

Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices(solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices(artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.

The Main Progress of Perovskite Solar Cells in 2020-2021

Perovskite solar cells(PSCs)emerging as a promising photovoltaic technology with high efficiency and low manufacturing cost have attracted the attention from all over the world.Both the efficiency and stability of PSCs have increased steadily in recent years,and the research on reducing lead leakage and developing eco-friendly lead-free perovskites pushes forward the commercialization of PSCs step by step.This review summarizes the main progress of PSCs in 2020 and 2021 from the aspects of efficiency,stability,perovskite-based tandem devices,and lead-free PSCs.Moreover,a brief discussion on the development of PSC modules and its challenges toward practical application is provided.

The origin and evolution of Y6 structure

During last several years,electron acceptors for organic sol-ar cells(OSCs)have experienced three major innovations.The first invention was a fused-ring electron acceptor(FREA),ITIC,reported by Zhan et al.in 2015,which consists of an in-dacenodithienothiophene(IDTT)donor core and two 3-dicy-anomethylene-1-indanone(IC)as the end-groups[1].ITIC cells exhibited comparable performance to PC61BM cells,and in-spired the development of hundreds nonfullerene acceptors(NFAs).The second breakthrough is the 14.08%power con-version efficiency(PCE)delivered by a low-bandgap non-fullerene acceptor COi 8DFIC with strong NIR absorption,invented by Ding et al.[2,3].The third star acceptor is Y6,developed by Zou et al.in 2019[4].Y6 and its derivatives(Y-series NFAs)are very promising[5,6].Ding et al.developed polymer donor D18 and its outstanding derivatives[7−10],and the D18:Y6 cells gave a PCE of 18.22%[7],which was the first time for OSCs to deliver PCEs over 18%.

Side chain engineering on D18 polymers yields 18.74%power conversion efficiency

Donor-acceptor(D-A)conjugated copolymers contain-ing fused-ring acceptor units demonstrate outstanding per-formance in organic solar cells(OSCs)[1−13].We have in-vented highly efficient D-A copolymer donors D18 and D18-Cl by using a fused-ring acceptor unit,dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2-c][1,2,5]thiadiazole(DTBT)[1,2].OSCs with D18 or D18-Cl gave power conversion efficiencies(PCEs)of 18.56%and 18.69%,respectively[3,4].Side chain engineering is an effective approach to improve the per-formance of conjugated polymers in optoelectronic devi-ces[14−16].The alkyl side chains not only determine polymers’solubility,but also influence their crystallinity and mobility.In this work,we develop two efficient donors D18-B and D18-Cl-B via side chain engineering on D18 polymers(Fig.1(a)).These donors offer PCEs up to 18.74%(certified 18.2%)in tern-ary OSCs.

Blade-coating Perovskite Films with Diverse Compositions for Efficient Photovoltaics

In this research highlight,recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV(i.e.widebandgap or small-bandgap perovskites with mixed cations and anions,2D/3D perovskites,Pb/Sn binary perovskites,and all-inorganic perovskites)for single-junction or tandem PSCs are discussed,with an emphasis on elucidating the distinct ink formulation engineering strategies,crystal growth mechanisms,crystallization kinetics,and optoelectronic properties of the different perovskite compositions.

Self-assembled monolayers in perovskite solar cells

Perovskite solar cells(PSCs)have attracted great attention due to excellent power conversion efficiency(PCE),low cost and simple solution processing.The certified PCE has reached 25.5% from the initial efficiency of 3.8%,being comparable to that of commercial crystalline silicon solar cells[1,2].The efficiency boosting is mainly ascribed to the excellent properties of halide perovskite materials,including suitable bandgaps,high absorption coefficient,long carrier diffusion length and high defect tolerance[3].

Defect engineering on all-inorganic perovskite solar cells for high efficiency

Perovskite solar cells based on organic–inorganic hybrid perovskite materials have become a research hotspot in photovoltaics field due to their outstanding power conversion efficiency (PCE)[1]. Nonetheless, the organic cations are volatile and have rotation freedom, which is not good for photoand thermal-stability of the devices.