Search

Raw data of first-principles calculations for "Homogeneous Surface Manipulation Enables Efficient and Scalable Inverted Perovskite Solar Cells" from Gaussian (G16,version C01) calculations to reproduce electrostatic potential (ESP) results of Fc-based compounds in Fig. 1a-b using MULTIWFN software(see Manual_3.3.8.pdf (mit.edu)or Multiwfn_quick_start.pdf (berkeley.edu)).

A hybrid dirhodium tetracarboxylate-based metal–organic polyhedron (MOP):PCBM electron transport layer is demonstrated to give rise to a 9% enhancement in power conversion efficiency for the derived inverted perovskite solar cell.

An effective way has been developed to realize high-performance perovskite solar cells. The relationship between deep-level defects, carrier mobility, charge extraction efficiency and fill factor (FF) was investigated, and the FF loss was analyzed.

ConspectusOrganic photovoltaics (OPVs) with a photoactive layer containing a blend of organic donor and acceptor species are considered to be a promising technology for clean energy owing to their unique flexible form factor and good solution processability that can potentially address the scalability challenges. The delicate designs of both donors and acceptors have significantly enhanced the power conversion efficiency of OPVs to more than 18%. Nonfullerene small-molecule acceptors (NFAs) have played a critical role in enhancing the short-circuit current density (JSC) by efficiently harvesting near-infrared (NIR) sunlight. To take full advantage of the abundant NIR photons, the optical band gap of NFAs should be further reduced to improve the performance of OPVs. Incorporating highly polarizable selenium atoms onto the backbone of organic conjugated materials has been proven to be an effective way to decrease their optical band gap. For example, a selenium-substituted NFA recently developed by our group has attained a JSC of approximate 27.5 mA cm-2 in OPV devices, surpassing those of most emerging photovoltaic systems. Inspired by this advance, we concentrate on the topic of selenium-containing materials in this Account to incite readers' interest in further exploring this series of materials.In this Account, we first compare the differences among chalcogen heterocycles and discuss the influence of fundamental electronic behavior on the collective photoelectrical properties of the resulting materials. The superior features of selenium-substituted materials are summarized as follows: (1) The large covalent radius of selenium can diminish the π-orbital overlap, rendering enhanced quinoidal resonance character and a narrowed optical band gap of resulting materials. (2) The selenium atom is more polarizable than sulfur owing to its larger and looser outermost electron cloud, enabling enhanced intermolecular Se-Se interaction and increased charge carrier mobility of relevant materials in the solid state. We then focus on summarizing the design rules for various categories of selenium-containing materials including polymer donors, small-molecule acceptors, and polymer acceptors, especially those composed of ladder-type polycyclic units. The motivation for incorporating selenium atoms into these materials and the structure-property relationships were thoroughly elucidated. Specifically, we discuss the changes in the optical band gap, charge carrier mobility, and molecular packing induced by selenium substitution and correlate the effects of these changes with the exciton behaviors, energy loss, and nanoscale film morphology of corresponding OPV devices. Furthermore, we point out the intrinsic stability of selenium-containing materials under maximum-power-point tracking and long-term photo- or thermostress and indicate their potential use in semitransparent and tandem solar cells. At the end, the prospect of future research focuses and the possible applications of selenium-containing materials in the OPV field are discussed.

Summary Interfacial engineering has been commonly used as an effective strategy to enhance device performance and stability of perovskite solar cells (PSCs). However, most of the materials used for interface engineering are based on organics, which may have concerns for the device's long-term stability. Therefore, we developed robust fluoro-terminated TiO2 nanosheets (F-TiO2 NSs) to work as interlayers between perovskite and electron-transporting layers in inverted PSCs. The flat NS morphology of F-TiO2 NSs enables close contact with perovskite with abundant surface fluoro groups, which can interact with undercoordinated lead and MA/FA ions to prevent the formation of cation vacancies and alleviate surface defects. As a result, a remarkable power conversion efficiency (PCE) of 22.86% can be achieved. The operational stability of devices with F-TiO2 NSs interlayers is also enhanced, which can maintain over 90% of their initial PCEs after being monitored at the maximum power point (MPP) for 1,000 h under day/night cycles.

Perovskite solar cells (PVSCs) have drawn great attention due to their high processability and superior photovoltaic properties. However, their further development is often hindered by severe nonradiative recombination at interfaces that decreases power conversion efficiency (PCE). To this end, a facile strategy to construct a 3D/2D vertical heterostructure to reduce the energy loss in PVSCs is developed. The heterostructure is contrived through the van der Waals integration of 2D perovskite ((BA)

All-polymer solar cells (all-PSCs) have achieved tremendous progress due to the recent advances of polymerized small molecule acceptors (PSMAs) and their power conversion efficiencies (PCEs) have reached over 14%. However, the practical applications of all-PSCs are still severely restricted by the lack of PSMAs with a broad absorption spectrum, high electron mobility, low energy loss, and good batch-to-batch reproducibility. Herein, a multi-selenophene-containing PSMA, namely PFY-3Se, based on a selenophene-fused SMA framework and a selenophene π-spacer was designed and developed. Compared to its thiophene analog PFY-0Se, PFY-3Se possesses a significantly red-shifted absorption (~30 nm), increased electron mobility, and improved intermolecular aggregation and packing. When matched with polymer donor PBDB-T, the PFY-3Se-based all-PSCs achieved an impressive PCE of 15.1% with both high short-circuit current density of 23.6 mA cm-2 and high fill factor of 0.737, and a low energy loss, which are among the best values in all-PSCs field reported so far and much better than those of thiophene analogs (PCE=13.0%). More importantly, PFY-3Se maintains similarly good batch-to-batch properties which is very helpful for realizing reproducible device performance. This is the first reported and also is very rare for the PSMAs so far which provides a potential candidate for efficient all-PSCs toward practical applications.

The oxygen evolution reaction (OER) is crucial to electrochemical hydrogen production. However, designing and fabricating efficient electrocatalysts still remains challenging. By confinedly coordinating organic ligands with metal species in layered double hydroxides (LDHs), an innovative LDHs-assisted approach is developed to facilely synthesize freestanding bimetallic 2D metal-organic framework nanosheets (2D MOF NSs), preserving the metallic components and activities in OER. Furthermore, the research has demonstrated that the incorporation of carboxyl organic ligands coordinated with metal atoms as proton transfer mediators endow 2D MOF NSs with efficient proton transfer during the electrochemical OH

Further enhancing the performance and stability of inverted perovskite solar cells (PSCs) is crucial for their commercialization. We report that the functionalization of multication and halide perovskite interfaces with an organometallic compound, ferrocenyl-bis-thiophene-2-carboxylate (FcTc 2 ), simultaneously enhanced the efficiency and stability of inverted PSCs. The resultant devices achieved a power conversion efficiency of 25.0% and maintained >98% of their initial efficiency after continuously operating at the maximum power point for 1500 hours under simulated AM1.5 illumination. Moreover, the FcTc 2 -functionalized devices passed the international standards for mature photovoltaics (IEC61215:2016) and have exhibited high stability under the damp heat test (85°C and 85% relative humidity).

Currently, the performance improvement for inverted perovskite solar cells (PVSCs) is mainly limited by the high open circuit voltage (VOC ) loss caused by detrimental non-radiative recombination (NRR) processes. Herein, we report a simple and efficient way to simultaneously reduce the NRR processes inside perovskites and at the interface by rationally designing a new pyridine-based polymer hole-transporting material (HTM), PPY2, which exhibits suitable energy levels with perovskites, high hole mobility, effective passivation of the uncoordinated Pb2+ and iodide defects, as well as the capability of promoting the formation of high-quality polycrystalline perovskite films. In absence of any dopants, the inverted PVSCs using PPY2 as the HTM deliver an encouraging PCE up to 22.41 % with a small VOC loss (0.40 V), among the best device performances for inverted PVSCs reported so far. Furthermore, PPY2-based unencapsulated devices show an excellent long-term photostability, and over 97 % of its initial PCE can be maintained after one sun constant illumination for 500 h.

In electrochemical water splitting process, integrating hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the same electrolyte with same catalyst is highly beneficial for increasing the energy efficiency and reducing the fabrication cost. However, most of the catalysts towards OER are unstable in acidic solution while HER is of poor kinetics in alkaline solution, which hinders the scale-up application of electro-catalytic water splitting. In this work, a CoP/Co3O4 heterostructure is firstly fabricated and then the O and P defects are involved to it via surface engineering (s-CoP/Co3O4). The as-prepared material is employed as the catalyst towards electrochemical water splitting in alkaline environment. In alkaline HER, a current density of -10 mA·cm-2 can be achieved at an overpotential of 106 mV vs. RHE. In OER process, the overpotential of s-CoP/Co3O4 electrode is only 211 mV vs. RHE at 10 mA·cm-2 in 1 M KOH, and the corresponding Tafel slope is only 58.4 mV/dec, so that the s-CoP/Co3O4 electrode could be used as the bifunctional catalyst for alkaline water splitting. This project provides a simple and low-cost approach to fabricate a Co-based heterojunction electrode with unsaturated metal sites to improve the electro-catalytic activities towards water splitting.

All-inorganic perovskite solar cells (PVSCs) have attracted intensive attention owing to their tunable bandgaps and excellent photo- and thermostability, making them promising absorbers in tandem solar cells (TSCs). Herein, we develop an all-inorganic perovskite/organic TSC with a wide bandgap all-inorganic perovskite CsPbI2.1Br0.9 and a narrow bandgap organic photoactive layer (PM6:Y6) serving as top and bottom sub cells respectively. The fabricated tandem solar cell demonstrated a remarkable PCE of 18.06%, with an open-circuit voltage (VOC) of 1.89 V, short-circuit current (JSC) of 12.77 mA cm−2, and fill factor (FF) of 74.81%, which is higher than that of both single junction PVSCs (14.43%) and organic solar cells (14.01%). Moreover, benefiting from the outstanding UV and thermal stability of inorganic perovskites, all-inorganic perovskite-based tandem devices showed superior stability under light and heat, with negligible degradation after 150 h of UV irradiation, 250 h under one sun illumination and 100 h of heating at 80 °C. This work demonstrates that all-inorganic perovskites are an appropriate candidate for the fabrication of efficient and stable TSCs.

Over the past few decades, gold-based materials have drawn extensive attention due to their intriguing physical/chemical properties and excellent performance in a broad range of applications. In particular, the remarkable technical progress in synthesis and characterization is promoting the rapid development of gold-based nanoalloys, which are of great significance in catalysis. In this review, we provide a brief overview of the recently reported gold-based nanoalloys, focusing on their general synthetic methods and potential catalytic applications. In particular, the general relationships between material structures/compositions and catalytic performances are discussed in representative chemical reactions, such as the carbon dioxide reduction reaction (CO2RR), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), small organic molecule oxidation reaction, carbon monoxide oxidation reaction, and typical heterogeneous catalytic reactions in chemical engineering. Furthermore, critical challenges and potential opportunities facing gold-based nanoalloys are proposed to provide possible inspiration for future material design towards high performance applications.

The interface and crystallinity of perovskite films play a decisive role in determining the device performance, which is significantly influenced by the bottom hole-transporting material (HTM) of inverted perovskite solar cells (PVSCs). Herein, this work reports a simple design strategy of polymer HTMs, which can modulate the wettability and promote the anchoring by introducing pyridine units into the polyarylamine backbone, so as to realize efficient and stable inverted PVSCs. The HTM properties can be effectively modified by varying the linkage sites of pyridine units, and 3,5-linked PTAA-P1 particularly demonstrates a more regulated molecular configuration for interacting with perovskites, leading to highly crystalline perovskite films with uniform back contact and reduced defect density. Dopant-free PTAA-P1-based inverted PVSCs have realized remarkable efficiencies of 24.89% (certified value: 24.50%) for small-area (0.08 cm

Nonfullerene acceptors (NFAs) have played an important role in the development of organic solar cells. However, the optical absorption of most NFAs is limited within 600–900 nm, prohibiting further...

Despite the notable progress in perovskite solar cells, maintaining long-term operational stability and minimizing potentially leaked lead (Pb2+) ions are two challenges that are yet to be resolved. Here we address these issues using a thiol-functionalized 2D conjugated metal–organic framework as an electron-extraction layer at the perovskite/cathode interface. The resultant devices exhibit high power conversion efficiency (22.02%) along with a substantially improved long-term operational stability. The perovskite solar cell modified with a metal–organic framework could retain more than 90% of its initial efficiency under accelerated testing conditions, that is continuous light irradiation at maximum power point tracking for 1,000 h at 85 °C. More importantly, the functionalized metal–organic framework could capture most of the Pb2+ leaked from the degraded perovskite solar cells by forming water-insoluble solids. Therefore, this method that simultaneously tackles the operational stability and lead contamination issues in perovskite solar cells could greatly improve the feasibility of large-scale deployment of perovskite photovoltaic technology. Two-dimensional conjugated metal–organic frameworks used as an electron-extraction layer enable the realization of highly stable perovskite solar cells with minimized lead ion leakage.

Recently, owing to the high energy density and excellent security, wearable Zn–air batteries (ZABs) have been known as one of the most prominent wearable energy storage devices. However, sluggish o...

In this work, two-dimensional conjugated covalent organic frameworks (2D-COF) based on a building block of tetraphenylethylene are successfully developed. Bicarbazole and pyrene moieties are respectively coupled with 4,4′,4′′,4′′′-(ethane-1,1,2,2-tetrayl)tetranilino (ETTA) via [4 + 4] solvothermal condensation conditions of 3,3′,6,6′-tetraformyl-9,9′-bicarbazole (Car-4CHO) and 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) to afford Car-ETTA and TFPPy-ETTA COFs. According to thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and N2 adsorption and desorption measurements, both Car-ETTA and TFPPy-ETTA COFs exhibit excellent thermal stability, highly crystalline structure, and high specific surface area, respectively. These findings are supported by force field and ab initio calculations. Furthermore, successful applications of these COFs in perovskite solar cells (PVSCs) are demonstrated owing to their well-conjugated properties and π–π interactions. While serving as interlayers in the devices, these COFs could effectively promote the interfacial charge dynamic to further optimize the resulting performance. Besides, certain interaction between COFs and perovskite also leads to an improved morphology and crystallinity of the perovskite layer, presenting defect passivation capability. As a result, we show that the performance of the COF-modified PVSC could be improved from 17.40 to 19.80%.

All-inorganic perovskite solar cells (PVSCs) have drawn increasing attention because of their outstanding thermal stability. However, their performance is still inferior than the typical organic-inorganic counterparts, especially for the devices with p-i-n configuration. Herein, we successfully employ a Lewis base small molecule to passivate the inorganic perovskite film, and its derived PVSCs achieved a champion efficiency of 16.1% and a certificated efficiency of 15.6% with improved photostability, representing the most efficient inverted all-inorganic PVSCs to date. Our studies reveal that the nitrile (C-N) groups on the small molecule effectively reduce the trap density of the perovskite film and thus significantly suppresses the non-radiative recombination in the derived PVSC by passivating the Pb-exposed surface, resulting in an improved open-circuit voltage from 1.10 V to 1.16 V after passivation. This work provides an insight in the design of functional interlayers for improving efficiencies and stability of all-inorganic PVSCs., There has been a hot competition to optimize the device performance for all-inorganic perovskite solar cells. Here Wang et al. employ a Lewis base molecule to suppresses the non-radiative recombination in the inverted device and achieve a champion efficiency of 16.1%.

Development of high-performance dopant-free hole-transporting materials (HTMs) with comprehensive passivation effects is highly desirable for all-inorganic perovskite solar cells (PVSCs). Squaraines (SQs) could be a candidate for dopant-free HTMs as they are natural passivators for perovskites. One major limitation of SQs is their relatively low hole mobility. Herein we demonstrate that polymerizing SQs into pseudo two dimensional (2D) p-π conjugated polymers could overcome this problem. By rationally using N,N-diarylanilinosquaraines as the comonomers, the resulting polysquaraine HTMs not only exhibit suitable energy levels and efficient passivation effects, but also achieve very high hole mobility close to 0.01 cm-2 V-1 s-1 . Thus as dopant-free HTMs for α-CsPbI2 Br-based all-inorganic PVSCs, the best PCE reached is 15.5 %, outperforming those of the doped-Spiro-OMeTAD (14.4 %) based control devices and among the best for all-inorganic PVSCs.

Organic thin-film solar cells have demonstrated a bright prospect for commercial applications, where organic photosensitizers act as the most important kernel. In the global motif of sustainable de...

Hybrid metal-halide perovskite solar cells (PVSCs) have drawn unprecedented attention during the last decade due to their superior photovoltaic performance, facile and low-cost fabrication, and potential for roll-to-roll mass production and application for portable devices. Through collective composition, interface, and process engineering, a comprehensive understanding of the structure-property relationship and carrier dynamics of perovskites has been established to help achieve a very high certified power conversion efficiency (PCE) of 25.5%. Apart from material properties, the modified heterojunction design and device configuration evolution also play crucial roles in enhancing the efficiency. The adoption and/or modification of heterojunction structures have been demonstrated to effectively suppress the carrier recombination and potential losses in PVSCs. Moreover, the employment of multijunction structures has been shown to reduce thermalization losses, achieving a high PCE of 29.52% in perovskite/silicon tandem solar cells. Therefore, understanding the evolution of the device configuration of PVSCs from single junction, heterojunction to multijunction designs is helpful for the researchers in this field to further boost the PCE beyond 30%. Herein, we summarize the evolution and progress of the single junction, heterojunction and multijunction designs for high-performance PVSCs. A comprehensive review of the fundamentals and working principles of these designs is presented. We first introduce the basic working principles of single junction PVSCs and the intrinsic properties (such as crystallinity and defects) in perovskite films. Afterwards, the progress of diverse heterojunction designs and perovskite-based multijunction solar cells is synopsized and reviewed. Meanwhile, the challenges and strategies to further enhance the performance are also summarized. At the end, the perspectives on the future development of perovskite-based solar cells are provided. We hope this review can provide the readers with a quick catchup on this emerging solution-processable photovoltaic technology, which is currently at the transition stage towards commercialization.

Interfaces between the perovskite active layer and the charge-transport layers (CTLs) play a critical role in both efficiency and stability of halide-perovskite photovoltaics. One of the major concerns is that surface defects of perovskite could cause detrimental nonradiative recombination and material degradation. In this work, we addressed this challenging problem by inserting ultrathin alkali-fluoride (AF) films between the tri-cation lead-iodide perovskite layer and both CTLs. This bilateral inorganic “walls” strategy makes use of both physical-blocking and chemical-anchoring functionalities of the continuous, uniform and compact AF framework: on the one hand, the uniformly distributed alkali-iodine coordination at the perovskite-AF interfaces effectively suppresses the formation of iodine-vacancy defects at the surfaces, thus reducing the trap-assisted recombination at the perovskite-CTL interfaces and therewith the open-voltage loss; on the other hand, the impermeable AF buffer layers effectively prevent the bidirectional ion migration at the perovskite-CTLs interfaces even under harsh working conditions. As a result, a power-conversion efficiency (PCE) of 22.02% (certified efficiency 20.4%) with low open-voltage deficit (

Among the emerging photovoltaic technologies, rigid perovskite solar cells (PSCs) have made tremendous development owing to their exceptional power conversion efficiency (PCE) of up to 25.7%. However, the record PCE of flexible PSCs (∼22.4%) still lags far behind their rigid counterparts and their mechanical stabilities are also not satisfactory. Herein, we report a highly efficient and stable flexible inverted PSC through modifying the interface between perovskite and hole transport layer (HTL) via Pentylammonium Acetate (PenAAc) molecule. Through synthetic manipulation of anion and cation, we show that the PenA

The incorporation of charged functional groups is effective to modulate the activity of molecular complexes for the CO