H^+ Passivation of Poly-Si Solar CellsProcessed by Different Annealing Processes

The effects of different annealing processes on the photovoltaic (PV) properties and the spectral response as well as minority carrier lifetime in the bulk of unanalyzed PF5 ion implantation poly-Si solar cells were investigated. The different hydrogen passivation effects of defects in poly-Si induced by three heat treatment processes are reported. We used RTA-rapid thermal annealing, YAG pulse laser annealing and CTSA-classical three-step annealing for this study. The results show that cells processed by RTA (800°C, 4 sec) achieved the best PV properties and spectral response among all annealed samples. Under this precess condition, no or few defects were induced in bulk. While RTA (>-850°C for 4 sec), CTSA as well as YAG laser processes induced defects of different nature and concentration in the bulk of cells. It is further shown that hydrogen ion implantation significantly improved, the performances of poly-Si cells. It is able to efficiently remove the YAG laser induced defects in bulk. However, it cannot completely passivate the defects induced by CTSA and RTA processes.

Toluene Processed All-Polymer Solar Cells with 18%Efficiency and Enhanced Stability Enabled by Solid Additive:Comparison Between Sequential-Processing and Blend-Casting

The emergence of polymerized small molecule acceptors(PSMAs)has significantly improved the performance of all-polymer solar cells(all-PSCs).However,the pace of device engineering lacks behind that of materials development,so that a majority of the PSMAs have not fulfilled their potentials.Furthermore,most high-performance all-PSCs rely on the use of chloroform as the processing solvent.For instance,the recent highperformance PSMA,named PJ1-γ,with high LUMO,and HOMO levels,could only achieve a PCE of 16.1%with a high-energy-level donor(JD40)using chloroform.Herein,we present a methodology combining sequential processing(SqP)with the addition of 0.5%wt PC_(71)BM as a solid additive(SA)to achieve an impressive efficiency of 18.0%for all-PSCs processed from toluene,an aromatic hydrocarbon solvent.Compared to the conventional blend-casting(BC)method whose best efficiency(16.7%)could only be achieved using chloroform,the SqP method significantly boosted the device efficiency using toluene as the processing solvent.In addition,the donor we employ is the classic PM6 that has deeper energy levels than JD40,which provides low energy loss for the device.We compare the results with another PSMA(PYF-T-o)with the same method.Finally,an improved photostability of the SqP devices with the incorporation of SA is demonstrated.

Step‑by‑Step Modulation of Crystalline Features and Exciton Kinetics for 19.2%Efficiency Ortho‑Xylene Processed Organic Solar Cells

With plenty of popular and effective ternary organic solar cells(OSCs)construction strategies proposed and applied,its power conversion efficiencies(PCEs)have come to a new level of over 19%in single-junction devices.However,previous studies are heavily based in chloroform(CF)leaving behind substantial knowledge deficiencies in understanding the influence of solvent choice when introducing a third component.Herein,we present a case where a newly designed asymmetric small molecular acceptor using fluoro-methoxylated end-group modification strategy,named BTP-BO-3FO with enlarged bandgap,brings different morphological evolution and performance improvement effect on host system PM6:BTP-eC9,processed by CF and ortho-xylene(o-XY).With detailed analyses supported by a series of experiments,the best PCE of 19.24%for green solvent-processed OSCs is found to be a fruit of finely tuned crystalline ordering and general aggregation motif,which furthermore nourishes a favorable charge generation and recombination behavior.Likewise,over 19%PCE can be achieved by replacing spin-coating with blade coating for active layer deposition.This work focuses on understanding the commonly met yet frequently ignored issues when building ternary blends to demonstrate cutting-edge device performance,hence,will be instructive to other ternary OSC works in the future.

Manipulating the Macroscopic and Microscopic Morphology of Large-Area Gravure-Printed ZnO Films for High-Performance Flexible Organic Solar Cells

Gravure printing is a promising large-scale fabrication method for flexible organic solar cells(FOSCs)because it is compatible with two-dimension patternable roll-to-roll fabrication.However,the unsuitable rheological property of ZnO nanoinks resulted in unevenness and looseness of the gravure-printed ZnO interfacial layer.Here we propose a strategy to manipulate the macroscopic and microscopic of the gravure-printed ZnO films through using mixed solvent and poly(vinylpyrrolidone)(PVP)additive.The regulation of drying speed effectively manipulates the droplets fusion and leveling process and eliminates the printing ribbing structure in the macroscopic morphology.The additive of PVP effectively regulates the rheological property and improves the microscopic compactness of the films.Following this method,large-area ZnO∶PVP films(28×9 cm^(2))with excellent uniformity,compactness,conductivity,and bending durability were fabricated.The power conversion efficiencies of FOSCs with gravure-printed AgNWs and ZnO∶PVP films reached 14.34%and 17.07%for the 1 cm^(2)PM6:Y6 and PM6∶L8-BO flexible devices.The efficiency of 17.07%is the highest value to date for the 1 cm^(2)FOSCs.The use of mixed solvent and PVP addition also significantly enlarged the printing window of ZnO ink,ensuring high-quality printed thin films with thicknesses varying from 30 to 100 nm.

High-Quality van der Waals Epitaxial CsPbBr_(3)Film Grown on Monolayer Graphene Covered TiO_(2)for High-Performance Solar Cells

Two-dimensional materials have been widely used to tune the growth and energy-level alignment of perovskites.However,their incomplete passivation and chaotic usage amounts are not conducive to the preparation of highquality perovskite films.Herein,we succeeded in obtaining higher-quality CsPbBr_(3)films by introducing large-area monolayer graphene as a stable physical overlay on top of TiO_(2)substrates.Benefiting from the inert and atomic smooth graphene surface,the CsPbBr_(3)film grown on top by the van der Waal epitaxy has higher crystallinity,improved(100)orientation,and an average domain size of up to 1.22μm.Meanwhile,a strong downward band bending is observed at the graphene/perovskite interface,improving the electron extraction to the electron transport layers(ETL).As a result,perovskite film grown on graphene has lower photoluminescence(PL)intensity,shorter carrier lifetime,and fewer defects.Finally,a photovoltaic device based on epitaxy CsPbBr_(3)film is fabricated,exhibiting power conversion efficiency(PCE)of up to 10.64%and stability over 2000 h in the air.

Accelerated Sequential Deposition Reaction via Crystal Orientation Engineering for Low-Temperature,High-Efficiency Carbon-Electrode CsPbBr_(3) Solar Cells

Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation engineering strategy of PbBr_(2)precursor film to accelerate its reaction with CsBr precursor during two-step sequential deposition of CsPbBr_(3)films.Such a novel strategy is proceeded by adding CsBr species into PbBr_(2)precursor,which can tailor the preferred crystal orientation of PbBr_(2)film from[020]into[031],with CsBr additive staying in the film as CsPb_(2)Br_(5)phase.Theoretical calculations show that the reaction energy barrier of(031)planes of PbBr_(2)with CsBr is lower about 2.28 eV than that of(O2O)planes.Therefore,CsPbBr_(3)films with full coverage,high purity,high crystallinity,micro-sized grains can be obtained at a low temperature of 150℃.Carbon-electrode PSCs with these desired CsPbBr_(3)films yield the record-high efficiency of 10.27%coupled with excellent operation stability.Meanwhile,the 1 cm^(2)area one with the superior efficiency of 8.00%as well as the flexible one with the champion efficiency of 8.27%and excellent mechanical bending characteristics are also achieved.

Non-destructive buffer enabling near-infrared-transparent inverted inorganic perovskite solar cells toward 1400 h light-soaking stable perovskite/Cu(In,Ga)Se_(2) tandem solar cells

Near-infrared(NIR)transparent inverted all-inorganic perovskite solar cells(PSCs)are excellent top cell candidates in tandem applications.An essential challenge is the replacement of metal contacts with transparent conductive oxide(TCO)electrodes,which requires the introduction of a buffer layer to prevent sputtering damage.In this study,we show that the conventional buffers(i.e.,small organic molecules and atomic layer deposited metal oxides)used for organic-inorganic hybrid perovskites are not applicable to all-inorganic perovskites,due to non-uniform coverage of the vulnerable layers underneath,deterioration upon ion bombardment and moisture induced perovskite phase transition,A thin film of metal oxide nanoparticles by the spin-coating method serves as a non-destructive buffer layer for inorganic PSCs.All-inorganic inverted near-infrared-transparent PSCs deliver a PCE of 17.46%and an average transmittance of 73.7%between 780 and 1200 nm.In combination with an 18.56%Cu(In,Ga)Se_(2) bottom cell,we further demonstrate the first all-inorganic perovskite/CIGS 4-T tandem solar cell with a PCE of 24.75%,which exhibits excellent illumination stability by maintaining 86.7%of its initial efficiency after 1400 h.The non-destructive buffer lays the foundation for efficient and stable NIR-transparent inverted inorganic perovskite solar cells and perovskite-based tandems.

Surface-functionalized hole-selective monolayer for high efficiency single-junction wide-bandgap and monolithic tandem perovskite solar cells

Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid)self-assembled monolayers(SAMs)are excellent hole-selective contact(HSC)materials with abilities to excel the charge-transferdynamics of perovskite solar cells(PSCs).Herein,we report a facile but powerful method to functionalize the surface of 2PACz-SAM,by which reproducible,highly stable,high-efficiency wide-bandgap PSCs can be obtained.The 2PACz surface treatment with various donor number solvents improves assembly of 2PACz-SAM and leave residual surface-bound solvent molecules on 2PACz-SAM,which increases perovskite grain size,retards halide segregation,and accelerates hole extraction.The surface functionalization achieves a high power conversion efficiency(PCE)of 17.62%for a single-junction wide-bandgap(~1.77 e V)PSC.We also demonstrate a monolithic all-perovskite tandem solar cell using surfaceengineered HSC,showing high PCE of 24.66%with large open-circuit voltage of 2.008 V and high fillfactor of 81.45%.Our results suggest this simple approach can further improve the tandem device,when coupled with a high-performance narrow-bandgap sub-cell.

Modeling the performance of perovskite solar cells with inserting porous insulating alumina nanoplates

Peng et al.[Science 379683(2023)]reported an effective method to improve the performance of perovskite solar cells by using thicker porous insulator contact(PIC)-alumina nanoplates.This method overcomes the trade-off between the open-circuit voltage and the fill factor through two mechanisms:reduced surface recombination velocity and increased bulk recombination lifetime due to better perovskite crystallinity.From arguments of drift-diffusion simulations,we find that an increase in mobility and carrier recombination lifetime in bulk are the key factors for minimizing the resistance-effect from thicker PICs and achieving a maximum power conversion efficiency(PCE)at approximately 25%reduced contact area.Furthermore,the partially replacement of perovskite films with thicker PICs would result in a reduction in short-current density,but the relative low refractive index of the PICs imbedded into the high refractive index perovskite creates light trapping structures that compensate for this loss.

Seed-assisted growth for high-performance perovskite solar cells:A review

The rapid increase in the power conversion efficiency(PCE)of perovskite solar cells(PSCs)is closely related to the development of deposition techinique for perovskite layer.The high-quality perovskite film enables efficient charge transportation and less trap states,which are eventually translated into enhanced device performance.Seed-assisted growth(SAG)is a potential technique for depositing highly-crystallized perovskite films with preferential crystal orientation among the numerous approaches related to crystallization modulation.In this review,we summarize the recent advances in the SAG technique for both one-step and two-step processed perovskite films.Additionally,seeding at the buried interface and on the top surface are also introduced.We present different seeds and their corresponding seeding mechanism in detail,such as inorganic nanomaterials,organic ammoniums,alkali metal halides,and perovskite seeds.Finally,challenges and perspectives are proposed to investigate the potential expansion of seeding engineering in high-performance PSCs,particularly large-area devices.

H-and J-aggregation of conjugated small molecules in organic solar cells

As H-and J-aggregation receive more and more attention in the research of organic solar cells(OSCs),especially in small molecular systems,deep understanding of aggregation behavior is needed to guide the design of conjugated small molecular structure and the fabrication process of OSC device.For this end,this review is written.Here,the review firstly introduced the basic information about H-and J-aggregation of conjugated small molecules in OSCs.Then,the characteristics of H-and J-aggregation and the methods to identify them were summarized.Next,it reviewed the research progress of H-and J-aggregation of conjugated small molecules in OSCs,including the factors influencing H-and J-aggregation in thin film and the effects of H-and J-aggregation on OPV performance.

Defect mediated losses and degradation of perovskite solar cells:Origin impacts and reliable characterization techniques

The rapid advancement of halide-based hybrid perovskite materials has garnered significant research attention,particularly in the domain of photovoltaic technology.Owing to their exceptional optoelec-tronic properties,they demonstrated power conversion efficiency(PcE)of over 25%in single junction solar cells.Despite the notable progress in PCE over the past decade,the inherent high defect density pre-senting in perovskite materials gives rise to several loss mechanisms and associated ion migration in per-ovskite solar cells(PsCs)during operational conditions.These factors collectively contribute to a significant stability challenge in PsCs,placing their longevity far behind for commercialization.While numerous reports have explored defects,ion migration,and their impacts on device performance,a com-prehensive correlation between the types of defects and the degradation kinetics of perovskite materials and PsCs has been lacking.In this context,this review aims to provide a comprehensive overview of the origins of defects and ion migration,emphasizing their correlation with the degradation kinetics of per-ovskite materials and PsCs,leveraging reliable characterization techniques.Furthermore,these charac-terization techniques are intended to comprehend loss mechanisms by different passivation approaches to enhance the durability and PCE of PSCs.

A short overview of the lead iodide residue impact and regulation strategies in perovskite solar cells

Lead iodide(PbI2) is a vital raw material for preparing perovskite solar cells(PSCs),and it not only takes part in forming the light absorption layer but also remains in the grain boundary as a passivator.In other words,the PbI2 content in the precursor and as formed film will affect the efficiency and stability of the PSCs.With moderate residual PbI2,it passivates the bulk/surface defects of perovskite,reduces the interfacial recombination,promotes the perovskite stability,minimizes the device hysteresis,and so on.Deficient PbI2 residue will reduce the interfacial passivation effect and device performance.In addition to facilitating the non-radiative recombination,over PbI2 residue can also lead to electronic insulation in the grain boundary and deteriorate the device performance.However,the impact and regulation of PbI2 residue on the device performance and stability is still not fully understood.Herein,a comprehensive and detailed review is presented by discussing the PbI2 residue impact and its regulation strategies(i.e., elimination,facilitation and conversion of the residue PbI2) to manipulate the PbI2 content,distribution and forms.Finally,we also show future outlooks in this field,with an aim to help further the progression of high-efficiency and stable PSCs.

Dimethylamine oxalate manipulating CsPbI_(3) perovskite film crystallization process for high efficiency carbon electrode based perovskite solar cells

Crystallization process determines the quality of perovskite films and the performances of resultant perovskite solar cells(PSCs).Dimethylamine oxalate has been proven as a multifunctional modulator,and is explored as an efficient additive in manipulating the crystallization process of CsPbI_(3) perovskite films.On one hand,oxalate serves as the precipitator that facilitates the nucleation process of intermediate.The larger size of intermediate is conductive to the larger size and smaller grain boundaries of resultant perovskite.On the other hand,in subsequent annealing process,the phase conversion and growth process of transient perovskite can be decelerated due to the strong interactions of oxalate with both dimethylamine cation(DMA^(+))and Pb^(2+).Due to the optimized crystallization kinetics,the morphology and quality of CsPbI_(3) perovskite films are comprehensively improved with lower defect concentrations,and charge recombination loss is effectively suppressed.Benefiting from the optimized crystal quality of perovskite films,the carbon electrode-based CsPbI_(3) PSCs exhibit a champion efficiency of 18.48%.This represents one of the highest levels among all hole transport layer-free inorganic perovskite solar cells.

Manipulating Crystal Growth and Secondary Phase PbI_(2)to Enable Efficient and Stable Perovskite Solar Cells with Natural Additives

In perovskite solar cells(PSCs),the inherent defects of perovskite film and the random distribution of excess lead iodide(PbI_(2))prevent the improvement of efficiency and stability.Herein,natural cellulose is used as the raw material to design a series of cellulose derivatives for perovskite crystallization engineering.The cationic cellulose derivative C-Im-CN with cyano-imidazolium(Im-CN)cation and chloride anion prominently promotes the crystallization process,grain growth,and directional orientation of perovskite.Meanwhile,excess PbI_(2)is transferred to the surface of perovskite grains or formed plate-like crystallites in local domains.These effects result in suppressing defect formation,decreasing grain boundaries,enhancing carrier extraction,inhibiting non-radiative recombination,and dramatically prolonging carrier lifetimes.Thus,the PSCs exhibit a high power conversion efficiency of 24.71%.Moreover,C-Im-CN has multiple interaction sites and polymer skeleton,so the unencapsulated PSCs maintain above 91.3%of their initial efficiencies after 3000 h of continuous operation in a conventional air atmosphere and have good stability under high humidity conditions.The utilization of biopolymers with excellent structure-designability to manage the perovskite opens a state-of-the-art avenue for manufacturing and improving PSCs.

Efficient PbS quantum dots tandem solar cells through compatible interconnection layer

Lead sulfide quantum dots(PbS QDs) hold unique characteristics, including bandgap tunability, solutionprocessability etc., which make them highly applicable in tandem solar cells(TSCs). In all QD TSCs, its efficiency lags much behind to their single junction counterparts due to the deficient interconnection layer(ICL) and defective subcells. To improve TSCs performance, we developed three kinds of ICL structures based on 1.34 and 0.96 e V PbS QDs subcells. The control, 1,2-ethanedithiol capped PbS QDs(PbS-EDT)/Au/tin dioxide(SnO_(2))/zinc oxide(Zn O), utilized SnO_(2) layer to obtain high surface compactness.However, its energy level mismatch causes incomplete recombination. Bypassing it, the second ICL(PbS-EDT/Au/Zn O) removed SnO_(2) and boosted the power conversion efficiency(PCE) from 5.75% to 8.69%. In the third ICL(PbS-EDT/poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA)/Au/Zn O), a thin layer of PTAA can effectively fill fissures on the surface of PbS-EDT and also protect the front cells from solvent penetration. This TSC obtained a PCE of 9.49% with an open circuit voltage of 0.91 V, a short circuit current density of 15.47 m A/cm~2, and a fill factor of 67.7%. To the best of our knowledge, this was the highest PCE achieved by all PbS QD TSCs reported to date. These TSCs maintained stable performance for a long working time under ambient conditions.

Constructing low-dimensional perovskite network to assist efficient and stable perovskite solar cells

The use of low-dimensional(LD)perovskite materials is crucial for achieving high-performance perovskite solar cells(PSCs).However,LD perovskite films fabricated by conventional approaches give rise to full coverage of the underlying 3D perovskite films,which inevitably hinders the transport of charge carriers at the interface of PSCs.Here,we designed and fabricated LD perovskite structure that forms net-like morphology on top of the underlying three-dimensional(3D)perovskite bulk film.The net-like LD perovskite not only reduced the surface defects of 3D perovskite film,but also provided channels for the vertical transport of charge carriers,effectively enhancing the interfacial charge transfer at the LD/3D hetero-interface.The net-like morphological design comprising LD perovskite effectively resolves the contradiction between interfacial defect passivation and carrier extraction across the hetero-interfaces.Furthermore,the net-like LD perovskite morphology can enhance the stability of the underlying 3D perovskite film,which is attributed to the hydrophobic nature of LD perovskite.As a result,the net-like LD perovskite film morphology assists PSCs in achieving an excellent power conversion efficiency of up to 24.6%with over 1000 h long-term operational stability.

Machine Learning-Assisted Fabrication of PCBM-Perovskite Solar Cells with Nanopatterned TiO_(2)Layer

To unlock the full potential of PSCs,machine learning(ML)was implemented in this research to predict the optimal combination of mesoporous-titanium dioxide(mp-TiO_(2))and weight percentage(wt%)of phenyl-C_(61)-butyric acid methyl ester(PCBM),along with the current density(J_(sc)),open-circuit voltage(V_(oc)),fill factor(ff),and energy conversion efficiency(ECE).Then,the combination that yielded the highest predicted ECE was selected as a reference to fabricate PCBM-PSCs with nanopatterned TiO_(2)layer.Subsequently,the PCBM-PSCs with nanopatterned TiO_(2)layers were fabricated and characterized to further understand the effects of nanopatterning depth and wt%of PCBM on PSCs.Experimentally,the highest ECE of 17.338%is achieved at 127 nm nanopatterning depth and 0.10 wt%of PCBM,where the J_(sc),V_(oc),and ff are 22.877 mA cm^(-2),0.963 V,and 0.787,respectively.The measured J_(sc),V_(oc),ff,and ECE values show consistencies with the ML prediction.Hence,these findings not only revealed the potential of ML to be used as a preliminary investigation to navigate the research of PSCs but also highlighted that nanopatterning depth has a significant impact on J_(sc),and the incorporation of PCBM on perovskite layer influenced the V_(oc)and ff,which further boosted the performance of PSCs.

Maskless fabrication of quasi-omnidirectional V-groove solar cells using an alkaline solution-based method

Silicon passivated emitter and rear contact(PERC) solar cells with V-groove texture were fabricated using maskless alkaline solution etching with in-house developed additive. Compared with the traditional pyramid texture, the V-groove texture possesses superior effective minority carrier lifetime, enhanced p–n junction quality and better applied filling factor(FF). In addition, a V-groove texture can greatly reduce the shading area and edge damage of front Ag electrodes when the V-groove direction is parallel to the gridline electrodes. Due to these factors, the V-groove solar cells have a higher efficiency(21.78%) than pyramid solar cells(21.62%). Interestingly, external quantum efficiency(EQE) and reflectance of the V-groove solar cells exhibit a slight decrease when the incident light angle(θ) is increased from 0° to 75°, which confirms the excellent quasi omnidirectionality of the V-groove solar cells. The proposed V-groove solar cell design shows a 2.84% relative enhancement of energy output over traditional pyramid solar cells.

Minimizing interfacial energy losses in inverted perovskite solar cells by a dipolar stereochemical 2D perovskite interface

Inverted perovskite solar cells(PSCs) have attracted broad research and industrial interest owing to their suppressed hysteresis,cost-effectiveness,and easy-fabrication.However,the issue of non-radiative recombination losses at the n-type interface between the perovskite and fullerene has impeded further improvement of photovoltaic performance.Here,we modify the n-type interface of FAPbI_(3) perovskite films by constructing a stereochemical two-dimensional(2D) perovskite interlayer,in which the organic cations comprise both pyridine and ammonium groups.The pyridine N donor can create stable bonding with the surface-uncoordinated Pb on the perovskite,thereby passivating the shallow-level defects and enhancing the air stability of the film.Furthermore,the pyridine N donor also offers a positive polar interface to decrease the surface work function of the perovskite film,enabling n-type modification.Ultimately,we employ a p-i-n photovoltaic(PV) device with the positive dipole interlayer at perovskite/fullerene contact and achieve remarkable photoelectric conversion efficiency(PCE) of 22.0%.