Liuyanfeng

Despite the breakthrough of over 22% power conversion efficiency demonstrated in organic–inorganic hybrid perovskite solar cells (PVSCs), critical concerns pertaining to the instability and toxicity still remain that may potentially hinder their commercialization. In this study, a new chemical approach using environmentally friendly strontium chloride (SrCl₂) as a precursor for perovskite preparation is demonstrated to result in enhanced device performance and stability of the derived hole-conductor-free printable mesoscopic PVSCs. The CH₃NH₃PbI₃ perovskite is chemically modified by introducing SrCl₂ in the precursor solution. The results from structural, elemental, and morphological analyses show that the incorporation of SrCl₂ affords the formation of CH₃NH₃PbI₃(SrCl₂)_x perovskites endowed with lower defect concentration and better pore filling in the derived mesoscopic PVSCs. The optimized compositional CH₃NH₃PbI₃(SrCl₂)_0.1 perovskite can substantially enhance the photovoltaic performance of the derived hole-conductor-free device to 15.9%, outperforming the value (13.0%) of the pristine CH₃NH₃PbI₃ device. More importantly, the stability of the device in ambient air under illumination is also improved.

A new compositional perovskite, CH₃NH₃PbI₃(SrCl₂)_0.1 with more compact morphology and lower defect concentration is presented. Consequently, a power conversion efficiency of 15.9% with enhanced stability is achieved by employing the structure of hole-conductor-free fully printable mesoscopic perovskite solar cell.

Interface engineering is an important aspect for the improvement of perovskite solar cells (PVSCs). The hole transport layer with good interface contact, transport capability, and matched energy level is indispensable and critical for high-performance photovoltaic devices. Herein, anode interface engineering with an excellent compatible bilayer of poly(3,4-ethylene dioxythiophene):poly(styrenesulfo-nate)/poly(3,4-ethylene dioxythiophene) (PEDOT:PSS/PEDOT) doped with grafted sulfonated-acetone–formaldehyde lignin (PEDOT:GSL) via a low-temperature and water-soluble process is presented. As a water-processable interface material, PEDOT:GSL exhibits higher conductivity, as well as better structural and electronic homogeneities compared with PEDTO:PSS. Consequently, the PEDOT:PSS/PEDOT:GSL bilayer with tuned energy level, optical properties, and the combination of the trap passivation of GSL at the anode/perovskite interface can greatly improve charge extraction ability and reduce the interface recombination. Simultaneously, the homogeneous perovskite film is fabricated through optimizing the annealing process. The device with the power conversion efficiency up to 17.80% is achieved, with 32.6% improvement compared to PEDOT:PSS-only device (13.42%). Our success to achieve high-performance inverted PVSCs provides new understanding of PEDOT:PSS, and also new guidelines for anode interface engineering to further advancement of PVSCs. This promising approach paves the way to realize solution processable highly efficient PVSCs for potential practical applications.

An anode interface engineering with excellent compatible poly(3,4-ethylene dioxythiophene) derivative bilayer via a low-temperature, water-soluble process is presented. Through the combination of tune energy level, optical properties, and trap passivation effect of grafted sulfonated-acetone-formaldehyde lignin at the hole transport layer/perovskite interface, the bilayer can greatly enhance the charge extraction and reduce the interface recombination rate. The device with remarkable power conversion efficiency up to 17.78% is achieved.

In recent years, high-efficient and low-cost perovskite solar cells (PSCs) have triggered a strong interest in the photovoltaic (PV) field. However, it is still challenging to develop cost-effective perovskite fabrication technologies for meeting the demands of mass production. The latest developed tubular chemical vapor deposition (CVD) with high level of controllability, versatility, and scalability has emerged as a promising preparation method for perovskites. Thus here we summarize the recent progress of perovskites grown by CVD approaches, and give emphasis not only to the preparation methods and reaction mechanisms but also to the related structures and specific properties, and also highlight their prospective PV application.

Recently, the cost-effective tubular chemical vapor deposition has been successfully introduced into the fabrication of perovskite solar cells and emerged as a promising technology for their future mass production. Herein, recent progress in the fields of material preparation, characterization, property and application are discussed.

The patterning of functional materials represents a crucial step for the implementation of organic semiconducting materials into functional devices. Classical patterning techniques such as photolithography or shadow masking exhibit certain limitations in terms of choice of materials, processing techniques and feasibility for large area fabrication. The use of self-assembled monolayers (SAMs) as a patterning tool offers a wide variety of opportunities, from the region-selective deposition of active components to guiding the crystallization direction. Here, we discuss general techniques and mechanisms for SAM-based patterning and show that all necessary components for organic electronic devices, i.e., conducting materials, dielectrics, organic semiconductors, and further functional layers can be patterned with the use of self-assembled monolayers. The advantages and limitations, and potential further applications of patterning approaches based on self-assembled monolayers are critically discussed.

The SAM-guided patterning of functional materials represents a powerful tool for the structuring of active layers in organic electronic devices. This approach is critically reviewed in view of the large-area processing of the different components of organic thin film transistors.

Organic–inorganic hybrid halide perovskites (e.g., MAPbI₃) have recently emerged as novel active materials for photovoltaic applications with power conversion efficiency over 22%. Conventional perovskite solar cells (PSCs); however, suffer the issue that lead is toxic to the environment and organisms for a long time and is hard to excrete from the body. Therefore, it is imperative to find environmentally-friendly metal ions to replace lead for the further development of PSCs. Previous work has demonstrated that Sn, Ge, Cu, Bi, and Sb ions could be used as alternative ions in perovskite configurations to form a new environmentally-friendly lead-free perovskite structure. Here, we review recent progress on lead-free PSCs in terms of the theoretical insight and experimental explorations of the crystal structure of lead-free perovskite, thin film deposition, and device performance. We also discuss the importance of obtaining further understanding of the fundamental properties of lead-free hybrid perovskites, especially those related to photophysics.

Recent progress on lead-free perovskite solar cells (PSCs) in terms of the theoretical insight and experimental explorations of the crystal structure of lead-free perovskites, thin-film deposition, and device performance is reviewed. The importance of understanding the fundamental properties of lead-free hybrid perovskites is discussed. Greater effort is needed to explore high-performance lead-free PSCs.

Using a “multifluorination” strategy, ambipolar donor–acceptor conjugated polymer with hole and electron mobility (μ_h and μ_e) up to 3.94 and 3.50 cm² V⁻¹ s⁻¹, respectively, and unipolar n-type donor–acceptor conjugated polymers with μ_e up to 4.97 cm² V⁻¹ s⁻¹ is synthesized with isoindigo as acceptor units.

In order to help readers stay up-to-date in the field, each issue of Progress in Photovoltaics will contain a list of recently published journal articles that are most relevant to its aims and scope. This list is drawn from an extremely wide range of journals, including IEEE Journal of Photovoltaics, Solar Energy Materials and Solar Cells, Renewable Energy, Renewable and Sustainable Energy Reviews, Journal of Applied Physics, and Applied Physics Letters. To assist readers, the lists is separated into broad categories, but please note that these classifications are by no means strict. Also note that inclusion in the list is not an endorsement of a paper's quality. If you have any suggestions please email Ziv Hameiri at ziv.hameiri@unsw.edu.au.

Metal halide perovskites, a class of crystalline semiconductors with unique optical and electronic properties, are emerging as potential solutions for low-cost photovoltaics and photonic sources in fields of solar cells, sensors, light-emitting diodes and lasers. Regardless of significant progress on device efficiency with the control over perovskite structures and film morphologies, unveiling the interface energetics and band alignment of these perovskite systems is indispensable for the performance optimization in the optoelectronic applications by grasping the photon harvest and charge transport processes. Herein we review the recent advances in the energetics of metal halide perovskite interfaces. The electronic properties of perovskite materials are addressed in terms of halide substitution, thermal annealing and substrate effects as well as trap states. The energy level alignments of interfaces between perovskite films and charge transport layers are then discussed, which is correlated to the photovoltaic properties in perovskite solar cells.

Recent advances in energetics in metal halide perovskite interfaces are reviewed with a combined discussion of electronic structures of metal halide perovskites and energy level alignment at perovskite/organic heterointerfaces through photoemission spectroscopy techniques. The energetics at the perovskite interfaces with various carrier transport materials is highlighted, suggesting the impact on photocurrent generation process in perovskite solar cells.

The solidification of hybrid perovskite (MAPbX₃, X = I, Br, Cl) inks is studied in situ by A. Amassian and co-workers in article 1604113, revealing a remarkably complex process mediated by strong solvent-solute interactions, the outcome of which is halide-dependent. The ink is shown to solidify within 15–20s of spinning, forming a highly solvated (60–70 vol%) precursor phase. Crystalline order of the precursor, or lack thereof, strongly impacts the morphological outcome of thermal conversion and the reproducibility of solar cells.

Organometal halide perovskite materials have become a superstar in the photovoltaic (PV) field because of their advantageous properties, which boost the power conversion efficiency (PCE) of perovskite solar cells (PSCs) from about 3.8% to above 22% in just seven years. Most importantly, such promising achievement is mainly based on its low-cost and solution-processed fabrication technique. One of the most promising and famous approaches to fabricating perovskite is a two-step sequential deposition method because precursor (e.g., PbI₂) deposition is controllable, versatile, and flexible. Due to tremendous efforts, great progress has been achieved on the two-step sequential deposition method, which helps to promote the development of PSCs. Herein, the progresses on the two-step sequential deposition method of perovskite layers is reviewed thoroughly. At first, the reaction process and principle is introduced and discussed. Then, the research on the deposition techniques, structures, and compositions of precursors (the first step) is presented. Subsequently, the developments on the conversion techniques, conversion solutions, and growth of large crystals at the second step are introduced. Finally, four important issues on the two-step sequential deposition method will be stated, accompanied with proposed solutions.

The two-step sequential deposition method is one of the most important deposition methods for the organometal halide perovskite layer in photovoltaic application. So far, great progress has been made on this method, which helps to promote the development of PSCs. Herein, its recent achievements are reviewed and the important issues are highlighted while proposing the corresponding solutions.