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Tin‐based perovskite is a competitive analog with lead halide perovskite, but there are significant gaps in power conversion efficiency (PCE) and stability between tin‐ and lead‐based perovskite solar cells. The characteristics of the easy oxidizability of Sn2+ and the rapid crystal growth for tin‐based perovskite are two major issues remained to be overcome. Herein, an additive (4‐pyridylamidoxime (4‐PyAO)) with multiple functional groups is introduced in the perovskite precursor solution. The oxidation of Sn2+ and the crystallization rate of perovskite are both retarded by 4‐PyAO addition. The prepared perovskite film is of high quality with fewer trap states and carrier recombination, and carrier extraction and transfer between the perovskite film and the adjacent carrier transport layer also become more efficient. As a result, the corresponding devices deliver the highest PCE of 9.02%, accompanied by short‐circuit current density, open‐circuit voltage, and fill factor of 19.90 mA cm−2, 0.63 V, and 72.48%, respectively. More importantly, the best device without encapsulation maintains 92% of its initial PCE after 2500 h aging test in nitrogen atmosphere, which may be attributed to a synergic effect among the different functional groups. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite solar cells (PSCs) have been the research focus due to their high thermal stability and proper band gap for tandem solar cells. However, their power conversion efficiency (PCE) is still lower than that of organic‐inorganic hybrid PSCs. Herein, a sacrificing dye (Rhodamine B isothiocyanate, RBITC) is developed to regulate the growth of perovskite film by in situ release of ethylammonium cations, isothiocyanate anions and benzoic acid molecules upon annealing and illumination. The ethylammonium cations can efficiently passivate surface defects. The isothiocyanate anions incorporate with uncoordinated Pb to regulate the crystallization process. The benzoic acid molecules facilitate the nucleation of the perovskite crystals. Especially, the illumination can accelerate the release of these beneficial ions/molecules to improve the quality of perovskite films further. After optimization with RBITC, a high open circuit voltage (VOC) of 1.24 V and a champion PCE of 20.95% are obtained, which are among the highest Voc and PCE values of CsPbI3 PSCs. Accordingly, the operational stability of the PSC devices is significantly improved. The results provide an efficient chemical strategy to regulate the formation of perovskite films in whole crystallization process for high performance all‐inorganic PSCs. [ABSTRACT FROM AUTHOR]

Solar cell efficiency and stability are two key metrics to determine whether a photovoltaic device is viable for commercial applications. The surface termination of the perovskite layer plays a pivotal role in not only the photoelectric conversion efficiency (PCE) but also the stability of assembled perovskite solar cells (PSCs). Herein, a strong chelate coordination bond is designed to terminate the surface of the perovskite absorber layer. On the one hand, the ligand anions bind with Pb cations via a bidentate chelating bond to restrict the ion migration, and the chelate surface termination changes the surface from hydrophilic to hydrophobic. Both are beneficial to improving the long‐term stability. On the other hand, the formation of the chelating bonding effectively eliminates the deep‐level defects including PbI and Pb clusters on the Pb‐I and FA‐I terminations, respectively, as confirmed by theoretical simulation and experimental results. Consequently, the PCE is increased to 24.52%, open circuit voltage to 1.19 V, and fill factor to 81.53%; all three are among the highest for hybrid perovskite cells. The present strategy provides a straightforward means to enhance both the PCE and long‐term stability of PSCs. [ABSTRACT FROM AUTHOR]

CsPbI2Br perovskite is known for its advantages over its organic‐inorganic hybrid counterpart including better thermal stability and appropriate bandgap for the front sub‐cell of tandem solar cell. However, its lower‐than‐satisfactory efficiency, problematic phase stability and sensitivity to moisture hinder its further advancement. Here, three kinds of glycine halides (Gly‐X: X = Cl, Br, and I) are strategically deigned to improve the performance of CsPbI2Br perovskite solar cells (PSCs). Systematic experimental and calculated results prove that a 2D/3D hybrid structure is formed, wherein the Gly‐X‐based 2D perovskite is mainly located at the CsPbI2Br grain boundaries, and the A‐sites of the 2D perovskite form strong bonds with the 3D perovskite to suppress ion migration by increasing its activation energy. As a result, a power conversion efficiency (PCE) of 17.26% was obtained with an open‐circuit voltage (VOC) of 1.33 V, which is among the best PCE values for the CsPbI2Br PSCs. In addition, the efficiency of encapsulated device decrease only by 14.1% after 340 h continuous illumination in ambient conditions, representing one of the most‐stable inorganic PSCs reported so far. This work provides important insights into designing passivating agents to address the issue of phase segregation for the development of highly stable perovskite optoelectronic devices. [ABSTRACT FROM AUTHOR]

Formamidinium methylammonium lead iodide (FAMAPbI3) perovskite has been intensively investigated as a potential photovoltaic material because it has higher phase stability than its pure FAPbI3 perovskite counterpart. However, its power conversion efficiency (PCE) is significantly inferior due to its high density of surface detects and mismatched energy level with electrodes. Herein, a bifunctional passivator, methyl haloacetate (methyl chloroacetate, (MClA), methyl bromoacetate (MBrA)), is designed to reduce defect density, to tune the energy levels and to improve interfacial charge extraction in the FAMAPbI3 perovskite cell by synergistic passivation of both CO groups and halogen anions. As predicted by modeling undercoordinated Pb2+, the MBrA shows a very strong interaction with Pb2+ by forming a dimer complex ([C6H10Br2O4Pb]2+), which effectively reduces the defect density of the perovskite and suppresses non‐radiative recombination. Meanwhile, the Br− in MBrA passivates iodine‐deficient defects. Consequently, the MBrA‐modified device presents an excellent PCE of 24.29%, an open‐circuit voltage (Voc) of 1.18 V (Voc loss ≈ 0.38 V), which is one of the highest PCEs among all FAMAPbI3‐based perovskite solar cells reported to date. Furthermore, the MBrA‐modified devices without any encapsulation exhibit remarkable long‐term stability with only 9% of PCE loss after exposure to ambient air for 1440 h. [ABSTRACT FROM AUTHOR]

It has been reported that an overlayer of lower dimensional perovskite can effectively improve the properties of 3D perovskite solar cells. Here, 4‐aminobutyric acid (C4I) and 6‐aminocaproic acid iodides (C6I) are introduced onto the surface of the perovskite layer, forming a low‐dimensional (LD) capping layer on the 3D perovskite films for high‐performance devices. It is found that C4I forms a 2D perovskite layer, while C6I forms a 1D perovskite layer on the 3D perovskite surface. By using the LD capping layers, the integrated perovskite films show passivated surface traps, reduced defect density, improved carrier lifetimes, and altered band alignment, leading to improved fill factor and open‐circuit voltage and, hence, significantly higher device efficiency. The devices with the C4I and C6I capping layers achieve solar cell efficiencies as high as 23.48% and 23.11%, respectively. In addition, bare devices with the C4I and C6I integration maintain 93.73% and 91.58%, respectively, of their initial efficiencies after exposure to the ambient atmosphere for 2000 h, demonstrating much better stability than the pristine 3D holding only 83.30% of its initial efficiency. It appears that this 2D capping is more suitable for enhancing 3D perovskite performance for general photoelectronic applications than the 1D capping. [ABSTRACT FROM AUTHOR]

As the power conversion efficiency (PCE) of perovskite solar cells (PSCs) is increased to as high over 25%, it becomes pre‐eminent to study a scalable process with wide processing window to fabricate large‐area uniform perovskite films with good light‐trapping performance. A stable and uniform intermediate‐state complex film is obtained by using tetramethylene sulfoxide (TMSO), which extends the annealing window to as long as 20 min, promotes the formation of a high‐quality perovskite film with larger grains (over 400 nm) and spontaneously forms the surface texture to result in an improved fill factor and open‐circuit voltage (Voc). Moreover, the superior surface texture significantly increases the long‐wavelength response, leading to an improved short‐circuit current density (Jsc). As a result, the maximum PCE of 21.14% is achieved based on a simple planar cell structure without any interface passivation. Moreover, a large area module with active area of 6.75 cm2 is assembled using the optimized TMSO process, showing efficiency as high as 16.57%. The study paves the way to the rational design of highly efficient PSCs for potential scaled‐up production. [ABSTRACT FROM AUTHOR]

• The B-doped induced recombination encountered in n-TOPCon solar cells. • B-doped profile divided into two characteristics: peak concentration and junction depth. • Cells with junction depth 0.75–1.0 μm and N max 1–1.5 × 1019 atoms/cm3 exhibited the best I-V. • After the optimization of B emitter, the solar cells reached a pilot efficiency greater than 23.4% A big challenge to improve the conversion efficiency of n-type solar cell is the recombination and electrical contacting of boron (B)-doped emitters in n-TOPCon solar cells. This work investigates the emitter dark saturation current density under the passivation layer (J 0e, passivated), the metallization-induced recombination current density under the metal contact (J 0e, metal), and the I – V parameters, including short-circuit current density (J sc), open circuit voltage (V oc), fill factor (FF) and efficiency (E ff) as functions of the peak concentration (N max) and junction depth of B-doped profile. We introduced the profile with the peak concentration of 1–1.5 × 1019 atoms/cm3 and a junction depth of 0.75–1.0 μm to improve the conversion efficiency of 23.4%. The results revealed that J sc, implied V oc (i V oc) and the contact resistance (ρ c) were negative correlated with the N max and junction depth. However, J 0e, passivated had a positive correlation with the same. The results from ρ c , J 0e along with the I – V showed the junction depth of emitter doping profiles need to exceed the corroded depth of Ag/Al paste to get a low ρ c , meanwhile, a low J 0e should be ensured. The results suggested theB-selective emitters were developed with a low ρ c and a low J 0e. After optimizing B-selective emitters and passivation processes, we obtained industry-grade TOPCon cells with E ff , V oc , J sc , and FF as high as 23.7%, 709 mV, 40.8 mA/cm2, and 82%, respectively. This optimized B-doped and simplified B-selective emitters processes can be commercially applied in photovoltaics. [ABSTRACT FROM AUTHOR]

• The optimal cleaning process combined inline-HF/HNO 3 and batch-polish solution. • Cells with low I Rev 0.15A have good optical property after optimal cleaning process. • Developed wraparound model addressed the principle of cleaning process. • A pilot efficiency >23.53% of TOPCon cells cleaned with optimal process. The use of tunnel oxide passivated contact (TOPCon) solar cells on the n-type Cz-Si wafers has thus far attracted more interest in the photovoltaics (PV) industry. However, the cells encounter the problems of wraparound appearance and edge leakage current. These phenomena can result in the decrease in the optical and electrical performance of the cells, such as open circuit voltage (V oc), short-circuit current density (J sc), and fill factor (FF). In this work, several cleaning processes were adopted to resolve the problems for cells. The wraparound model and experimental results indicated that an effective cleaning process was carried out and revealed the correlation between the removal of the wraparound film and the edge junction layer on the surface of wafers. The optimized cleaning process did not destroy the boron-doping layer on the front side, and the poly-Si layer on the rear side. This process combined an inline etching process of HF/HNO 3 treatment and a batch-type etching process of the KOH/polish additives solution treatment, which could effectively solve the problems associated with optical properties and achieve a low reversed-biased junction leakage current (I Rev) 0.15 A at −14.5 V. After optimization of the rear surface recombination and the boron diffusion processes, industrial-type TOPCon cells at the present pilot line were obtained with the efficiency (E ff), V oc , J sc and FF of 23.53%, 706 mV, 40.65 mA/cm2 and 82.02%, respectively. This optimized cleaning process could be applied and promoted in the PV industry. [ABSTRACT FROM AUTHOR]

The charge/ion transfer and structural stability of silicon suboxide (SiO X) for lithium-ion batteries (LIBs) are plaguing. Titanate oxide (TiO 2) shows zero strain and high ion diffusion for lithiation, promising for improving its electrochemical properties. Herein, hybrid TiO X /SiO X @C (local reduction of TiO 2 for TiO X) was prepared via magnesiothermic reaction and self-assembled as hierarchical microspheres. The embedded TiO X and hierarchical structures buffer the volume-expansion-induced strain of TiO X /SiO X @C for high structural integrity. Oxygen-vacancy sites around Ti and Si atoms for charge transfer tunnel and the heterostructure for fast interfacial charge response improve its electronic conductivity. The introduction of locally reduced Ti atoms alters oxygen structural dispersion, further reducing Li diffusion barriers. Even, the inevitable crack of TiO X /SiO X induces its exposure to the electrolyte, facilitating a compact solid electrolyte interphase layer for stable electrochemical performance. Thus, its open-circuit voltage curve displays a low lithiation platform due to its low polarization for Si-based anodes. These synergetic findings deliver the optimal TiO X /SiO X @C with high cycling stability (951.6 mAh g−1 at 1A g−1 after 1000 cycles with a capacity retention of ∼87.7%) and superb rate capability (516.5 mAh g−1 at 4 A g−1). This work provides a deep understanding of charge/ion kinetics for SiO X -based anodes of LIBs. [Display omitted] • Ti is found to assist the reduction of TiO X /SiO X with a high crystalline Si phase. • Oxygen-vacancy TiO X improves the ion/charge kinetics of the electrodes. • TiO X phase is zero strain upon lithiation, stabilizing its cycling structure. • The covalent interface is beneficial to form a stable SEI layer. • TiO X /SiO X @C delivers a specific capacity of 951.6mAh/g at 1A/g after 1000 cycles. [ABSTRACT FROM AUTHOR]

Chemical bath–deposited cadmium sulfide (CBD-CdS) is the most widely used buffer layer material for antimony selenosulfide (Sb 2 (S,Se) 3) photovoltaic devices, but its medium band gap, large band gap offset with transparent conducting oxides, and surface defects must be addressed to improve its applicability. Hexagonal CdS films (60 nm thick) prepared using the thermal evaporation method were used as the buffer layers of Sb 2 (S,Se) 3 photovoltaic devices. Compared with CBD-CdS (60 nm thick), thermal evaporation–deposited CdS (TED-CdS) films have a larger band gap and fewer surface defects. The Sb 2 (S,Se) 3 film deposited on TED-CdS is more compact, and its 1D ribbons are stacked more vertically to the substrate. The band gap offset between CdS and fluorine-doped tin oxide glass decreases from 0.76 eV (CBD-CdS) to 0.60 eV (TED-CdS). Therefore, suppressed electron trap density and charge recombination, as well as improved light harvesting, are achieved. By replacing CBD-CdS with TED-CdS, the best device efficiency increases from 6.14 % to 7.16 %, with the open circuit voltage, short-circuit current density, and fill factor increasing from 0.660 V, 15.96 mA/cm2, and 58.37 % to 0.664 V, 17.39 mA/cm2, and 62.85 %, respectively. The device stability and reproducibility are also improved. [Display omitted] • Hexagonal CdS buffer layer was prepared by thermal evaporation (TED-CdS). • TED-CdS has larger band gap than chemical bath deposited CdS (CBD-CdS). • TED-CdS is conducive to the growth of [221]-oriented Sb 2 (S,Se) 3 grains. • TED-CdS decreases the band gap offset between CdS and FTO. • Improved light harvesting and suppressed charge recombination are achieved. [ABSTRACT FROM AUTHOR]

Abstract: Ionic liquid-tethered graphene oxide (IL-GO) are prepared by tethering 1-(3-aminopropyl)-3-methylimi-dazolium bromide to graphene oxide (GO), and followed by anion-exchange with bis(trifluoromethanesulfonyl)imide ions (TFSI−). Environmental friendly ionic liquid-based composite electrolyte for dye sensitized solar cells (DSSCs) without volatile organic solvents is prepared from IL-GO and 1-propyl-3-methylimidazolium iodide (PMII). Incorporation of proper amount of IL-GO significantly increased the conductivity of the electrolyte, the open circuit voltage, the short circuit current density and the conversion efficiency of DSSCs. The dye-sensitized solar cells (DSSCs) containing 4 wt% of IL-GO composite electrolytes show an overall power conversion efficiency of 7.04% under simulated AM 1.5 solar spectrum irradiation at 100 mW cm−2. These results indicate that the DSSCs based on IL-GO/IL composite electrolytes could overcome the drawbacks of volatile liquid electrolytes, and offer a feasible method to fabricate DSSCs in future practical applications. [Copyright &y& Elsevier]

CsPbI 2 Br perovskites are promising candidates for photovoltaic applications owing to the trade-off between the optoelectronic properties and phase stability of cesium-based inorganic perovskites. However, the major shortcomings of CsPbI 2 Br perovskite solar cells (PSCs), namely energy loss and poor moisture resistance, still need to be addressed. In this work, reversible degradation-assisted decoration with Cs 4 PbBr 6 nanocrystals (NCs) is used to passivate the perovskite/hole transporting material (HTM) interface. Moisture-induced Cs 4 PbBr 6 decomposition products (CsPbBr 3 and CsBr) and CsPbI 2− x Br 1+ x (x > 0), generated as a result of halide anion exchange between CsPbI 2 Br and Cs 4 PbBr 6 or its decomposition products, are found to improve the quality of the CsPbI 2 Br film and suppress the trap state density. In addition, the decoration achieves desirable energy-level alignments at the CsPbI 2 Br/HTM interface and raises the Fermi level of the CsPbI 2 Br film, thereby strengthening the built-in electric field between the perovskite and HTM. As a result, the optimized CsPbI 2 Br PSC has a champion efficiency of 15.52% with an open-circuit voltage of 1.30 V (mean value: 1.29 V). The unencapsulated CsPbI 2 Br film and device both exhibit high air stability (∼40% humidity), and the latter retains 90% of its initial efficiency after a 500 h aging test. [Display omitted] • Decoration with Cs 4 PbBr 6 nanocrystals and subsequent reversible degradation. • The decoration improves crystal quality and suppresses trap state density. • Strengthening of the built-in electric field are also achieved by the decoration. • PSC V OC and moisture stability are simultaneously improved. [ABSTRACT FROM AUTHOR]

• A small molecule hole transport materials (HTM, DFBT-PMTP) has been designed. • DFBT-PMTP canbe applied without doping and annealing in perovskites solar cells. • The efficiency of the corresponding p-i-n device reaches to as high as 21.23%. Hole transport materials (HTMs) play an important role in perovskites solar cells (Pero-SCs) which can greatly affect the stability and power conversion efficiency (PCE). While most of the efficient HTMs need doping (which results in poor stability) or the treatment of thermal annealing (which increases the complexity of the device fabrication process). In this work, we synthesized a small molecule HTM DFBT-PMTP based on 3,3′-difluoro-2,2′-bithiophene and applied it as HTM without the need for doping and thermal annealing in p-i-n Pero-SCs with the structure of ITO/HTM/MAPbI 3−x Cl x /C 60 /BCP/Ag. The PCE of the corresponding devices achieves a high value of 21.23% (19.8% for the PTAA-based reference ones), with an open-circuit voltage of 1.17 V and a high fill factor of 82.28%, which is to date among the highest values for the p-i-n MAPbI 3−x Cl x –based Pero-SCs. Interestingly, the PCE of the devices declined to 18.65 and 15.5%, while the annealing temperature of DFBT-PMTP increased to 100 and 150 °C, respectively. And the reasons for this abnormal phenomenon have been investigated including the intrisinc properties, the energy levels of MAPbI 3−x Cl x on top and the decices performance of the DFBT-PMTP films without annealing and annealed at 100 and 150 °C, respectively. The results revealed that the precise molecular structure design for the HTMs can make huge changes in the corresponding photovoltaic properties and fabrication process due to the effects on the top perovskites. [ABSTRACT FROM AUTHOR]

As a new general photovoltaic, antimony selenide (Sb 2 Se 3) thin-film solar cell is now limited by the open-circuit voltage (V oc). In this study, an ultra-thin CdS:Al film obtained by co-sputtering CdS and Al targets as a N+ layer was employed in Sb 2 Se 3 thin-film solar cells. The desposition condition of CdS:Al was optimised and solar cells with FTO/CdS:Al/CdS/Sb 2 Se 3 /Au structure were fabricated. Compared with the device without an N+ layer, the device with the N+ layer exhibited preferable photoelectric response, enlarged depletion-region width, better diode quality and reduced carrier recombination. As a result, improvements of 19% in V oc and 30% in efficiency of the Sb 2 Se 3 thin-film solar cell were realised. • High electrical concentration of CdS films has been obtained with adding Al element. • The N+/NP structure is beneficial to reduce carrier recombination and promote carrier collection. • The CdS:Al thin film as the N+ layer enhances the EQE response and improves the V oc and FF of Sb2Se3 thin film solar cells. [ABSTRACT FROM AUTHOR]

To implement the commercialization of perovskite solar cells (pero-SCs) in the future, employing high-efficiency and low-cost hole-transporting materials (HTMs) is one of crucial factors. Herein, through investigating the electronic structure and geometry of the molecular structure with density functional theory calculation, a dibenzo[ b,d ]furan-centred molecular hole-transporting material (termed DBFMT) is synthesized from commercial monomers with a relatively low cost of approximately US$35 per gram in laboratory. This dopant-free HTM is applied in the planar p-i-n pero-SCs with a structure of ITO/DBFMT/perovskite (MAPbI 3)/C 60 /BCP/Ag. Based on the different concentration of DBFMT, the corresponding top perovskite grain sizes are different. After optimization, the power conversion efficiency (PCE) reaches as high as 20.51%, with a short-circuit current density of 23.70 mA cm−2, an open circuit voltage of 1.07 V, and a fill factor of 80.48%. As far as we know, the PCE of 20.51% is among the highest efficiency for the p-i-n pero-SCs based on the dopant-free HTMs. Image 1 • A dibenzo[ b,d ]furan-centred linear hole-transporting material (L-HTM) was synthesized. • This dopant-free L-HTM was applied in planar p-i-n perovskite solar cells (pero-SC). • The highest efficiency of 20.51% achieved among the dopant-free L-HTM-based pero-SC. [ABSTRACT FROM AUTHOR]