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Inverted (p‐i‐n) perovskite solar cells (PSCs) are advantageous in terms of easy fabrication, low‐temperature processibility, negligible hysteresis, and excellent compatibility with the tandem devices in comparison with the regular (n‐i‐p) counterparts. Hole‐blocking layer is crucial for efficient electron transport of inverted PSCs, and only a single hole‐blocking layer of bathocuproine (BCP) is used typically. Herein, bis[2‐(diphenylphosphino)phenyl] ether oxide (DPEPO) with a deep highest occupied molecular orbital (HOMO) energy level is incorporated atop of perovskite film as an auxiliary hole‐blocking layer, resulting in an enhanced electron transport of inverted PSC devices. The P=O group within DPEPO can coordinate with Pb2+ cations of perovskite, leading to passivation of surface defects of perovskite. Besides, incorporation of DPEPO hole‐blocking layer prohibits undesired hole transport from perovskite to PCBM electron transport layer (ETL), thus suppressing non‐radiative electron–hole recombination. As a result, combined with BCP hole‐blocking layer, inverted PSC devices based on double hole‐blocking layers exhibit a decent power conversion efficiency (PCE) of 24.17% with a high open‐circuit voltage (Voc) of 1.15 V which dramatically surpasses that based on single hole‐blocking layer (22.26%). Moreover, incorporation of hydrophobic DPEPO helps to improve the ambient and thermal stabilities of inverted PSC devices. [ABSTRACT FROM AUTHOR]

Organic semiconductors with noncovalently conformational locks (OSNCs) are promising building blocks for hole‐transporting materials (HTMs). However, lack of satisfied neighboring building blocks negatively impacts the optoelectronic properties of OSNCs‐based HTMs and imperils the stability of perovskite solar cells (PSCs). To address this limitation, we introduce the benzothieno[3,2‐b]thiophene (BTT) to construct a new OSNC, and the resulting HTM ZS13 shows improved intermolecular charge extraction/transport properties, proper energy level, efficient surface passivation effect. Consequently, the champion devices based on doped ZS13 yield an efficiency of 24.39 % and 20.95 % for aperture areas of 0.1 and 1.01 cm2, respectively. Furthermore, ZS13 shows good thermal stability and the capability of inhibiting I− ion migration, thus, leading to enhanced device stability. The success in neighboring‐group engineering can triggered a strong interest in developing thienoacene‐based OSNCs toward efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

In recent years, perovskite solar cells have achieved high efficiency in small areas, but the industrialization of perovskite solar cells is still hampered by the efficiency loss of cells during area scaling. Series modules are currently the most widely used and effective modular process for perovskite solar cells, a process that requires the patterning of the layer stack in individual cells. This interconnection scheme consists of three lines, P1–P3, which are ablated using a pulsed laser beam. In this work, we developed an efficient perovskite module with a high geometric fill factor (GFF) based on a two-step spin-coating method by optimizing the laser ablation step. We constructed the entire device structure by means of a picosecond green pulsed laser, meanwhile, the dead area is greatly reduced by optimizing the parameters and process, and finally achieving an ultra-high GFF of over 99%. In addition, we investigated the effect of poor P2 and P3 ablation on the perovskite solar modules and compared the performance of the module before and after ablation optimization. We finally obtained a maximum photoelectric conversion efficiency of 22.79% with an aperture area of 12.6 cm2. Concurrently, we conducted electrocatalytic hydrogen production experiments on the prepared perovskite solar modules, and the experimental results have also shown excellent performance and good prospects. [ABSTRACT FROM AUTHOR]

A precursor film with a Cu gradient was prepared in order to improve the quality of the absorber film produced by sputtering CIGS targets when using glass substrates. Two ceramic quaternary targets with different copper content were used for alternatively sputtering to get a bi-layer precursor film with a Cu gradient; meanwhile, the crystallization property and cell performance were studied. This was done in order to study the activities of the Cu element in the precursor layer before and after selenization. The film states of the temperature-rise period and high temperature selenization period were investigated. The appropriate structure of the precursor film was the Cu-rich layer underneath the Cu-poor layer. The Cu–Se phase, which is important for the crystalline property, can be produced in the Cu-rich layer under the heating period. The Cu-poor layer on the top reacts with the Cu-Se compound in the annealing process at a high temperature, and the big grain size of the absorber layer can be obtained due to Cu diffusion promoted by the gradient in the precursor film, as well as better conversion efficiency. This result shows that constructing the precursor film with a Cu gradient by sputtering different quaternary CIGS targets is a very promising fabrication method to obtain high-performance solar-cell devices with a good crystallization property under an annealing temperature of 550 °C and is suitable for further industrialized application. [ABSTRACT FROM AUTHOR]

High coverage film could be obtained from precursor film PEDOT: PSS-based inverted perovskite solar cell, via decreasing the amount of residual DMSO or mediating the evaporation rate of DMSO with continuous gradient annealing (GA) process at 65°C–85°C (heating rate of 20°C/5 min). • A remanent solvent management strategy was employed to prepare uniform film. • The influence of residual DMSO on the properties of the MAPbI 3 film was investigated. • High device reproducibility was obtained with gradient thermal annealing. Perovskite solar cells (PSCs) have been attracting tremendous attention due to ease of processing, flexibility, and high performance. Dimethyl sulfoxide (DMSO) and N, N-dimethylformamide (DMF) are the two most widely used solvents to dissolve perovskite precursors. Here, we investigate the impact of residual amount and evaporation rate of the DMSO inside the precursor films on the microstructure of the ultimate perovskite films. We decouple the DMSO and DMF solvents and demonstrate that DMSO component exhibits great and dominant influence on the final film morphology by using quasi in-situ photoluminescence (PL) measurement and X-ray diffraction (XRD) characterization of the wet films after spin-coating. Much more smooth and uniform perovskite films are obtained by careful management of remanent solvent, including decreasing residual amount by shelving the precursor films prior to heating and retarding the evaporation of the solvent via adopting a gradient annealing (GA) process. In consequence, the as-prepared PEDOT: PSS-based inverted PSCs yield a champion efficiency of 15.59% with high reproducibility. This work shows great potential in preparing high-quality perovskite films through a simple remanent solvent management engineering. [ABSTRACT FROM AUTHOR]

Ionic defects at the surfaces of organolead halide perovskite films are detrimental to both the efficiency and stability of perovskite solar cells (PSCs). Herein, sodium p‐toluenesulfonate (STS) is applied during the surface modification of perovskite layer for the first time, leading to the efficient surface passivation of the perovskite film and consequently significant enhancements in both efficiency and stability of mixed‐cation PSC devices. Upon incorporating STS atop the perovskite layer, the power conversion efficiency of the Cs0.05MA0.12FA0.83PbI2.55Br0.45 (abbreviated as CsMAFA) mesoporous‐structure mixed‐cation PSC devices improves from 18.70% to 20.05% with reduced hysteresis. The sulfonate (–SO3−) anion of STS coordinates with the Pb2+ of CsMAFA perovskite, and the Na+ cation of STS electrostatically interacts with the anions (I−/Br−) of CsMAFA perovskite, resulting in the surface passivation of the CsMAFA perovskite film with reduced electron and hole trap state densities. In addition, STS modification induces an upshift of the valence band of perovskite, facilitating hole extraction from the perovskite layer to the hole transport layer with suppressed interfacial charge recombination. Moreover, such a trap state passivation of perovskite film leads to improvement of the ambient stability of PSC devices. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) based on planar SnO2 (p‐SnO2) demonstrate excellent performance due to the superior properties of SnO2 as electron transporting layer (ETL). However, at present mesoporous SnO2 (m‐SnO2) still lags behind p‐SnO2 due to problems in the fabrication process of m‐SnO2. In this paper, a new strategy for preparing m‐SnO2 ETL is introduced which owns two valuable features: First, it applies a low temperature process to make mesoporous structure, which favors preserving the pristine properties of the raw SnO2 nanocrystals. Second, the degree of porosity and roughness of the m‐SnO2 layer can be well controlled, making it friendly to the following deposition process of PSCs. The performance of the PSCs based on the m‐SnO2 ETL prepared from this strategy shows an obvious improvement which is mainly from the improvement in Jsc and FF, suggesting a higher carrier collection efficiency for the m‐SnO2 ETL. The relevant characterizations including PL, TRPL, EIS, and KPFM confirm that the m‐SnO2 ETL possesses stronger electron extraction capability than the p‐SnO2 ETL. Hence, the proposed strategy can manifest the advantages of m‐SnO2 ETL meanwhile refrain its negative impacts, and thus promote the progress of the m‐SnO2 ETL‐based PSCs. [ABSTRACT FROM AUTHOR]

Metal hybrid halide perovskite solar cells (PSCs) are very sensitive to air, and it is challenging to obtain air-processed, air-stable, and highly crystalline perovskite films. Photovoltaic performance decays dramatically due to air humidity influence with power conversion efficiency (PCE) of most air-processed PSCs < 15%. In this work, we develop a facile method to air-processed, highly crystalline (MA0.2FA0.8PbI3)1.0(CsPbBr3)0.05 perovskite films in ambient air with large grain size and low trap density based on mix-cation single crystal engineering. This method shows 75% increase in grain size and 28% decrease in trap density than conventional molecule/ion solution mixing-processed method. The large grain, low trap density, andhigh crystalline perovskite films result in high-efficient and air-stable PSCs. Consequently, the PCE increases to 36.7% from 12.56% for conventional molecule/ion solution mixing-processed devices and to 17.17% for single crystal engineering-based ones. Furthermore, benefiting from high moisture resistance of mix-cation single crystal engineering-based films, the PSC air stability has been improved significantly and 72% of the initial performance retains after 40 days of storage in ambient environment with a relative humidity of 60% at 25 °C without any encapsulation, with a 26% slower degradation rate than conventional solution-mixing method. [ABSTRACT FROM AUTHOR]

High-performance perovskite solar cell processed in ambient air is a big challenge due to the sensitivity of perovskite films to air. Many defects are generated easily at grain boundaries and in the perovskite films by conventional molecular/ion precursor solution mixing methods (i.e., solution mixing-based method), which restrict its stability in air and photovoltaic performance with most power conversion efficiency less than 15%. In this work, we develop a facile method for air-processed, highly crystalline, quasi-3D perovskite film with large grain size (over 6.6 times bigger than that from control conventional method) and improved ambient air stability by phenylethylammonium (PEA)-doped MA1−xPEAxPbI3 perovskite crystal engineering. Furthermore, benefiting from PEA+ doping and crystal engineering, the trap density decreases 50% compared with control. Consequently, with the optimal concentration of PEA doping, the power conversion efficiency increases from 15.6% for conventional solution mixing-based perovskite solar cells to 17.6% for crystal engineering-based ones with significantly improved moisture stability. The perovskite crystal engineering-based solar cells without any encapsulation retain 75% of the initial performance after 30-day storage in ambient air under a relative humidity of 50 ± 10%, and two times faster degradation rate is observed for control, conventional solution mixing-based perovskite solar cells when compared with crystal engineering-based ones. [ABSTRACT FROM AUTHOR]

Lead iodide (PbI 2) as a defect passivation in perovskite thin films can reduce halide vacancies and improve the performance of perovskite solar cells. However, excess PbI 2 can hurt the device's performance. In the case of perovskite films prepared by two-step sequential deposition, excess PbI 2 is distributed on the surface of perovskite film. The photo-decomposition of PbI 2 and the formation of surface energy barriers can hinder charge transfer in the device, leading to reduced device performance and accelerated device degradation. Inspired by the use of surfactants to control the morphology of perovskite nanocrystals, a dual-functional surfactant (oleamide) was introduced to control the distribution of excess PbI 2 on perovskite films. By adding oleamide, the aggregation distribution of PbI 2 was successfully achieved at the perovskite grain boundaries (GBs), forming a Type-I band alignment and reducing the trap density, thereby prolonging the carrier lifetime. The results show that the power conversion efficiency (PCE) of the device increased from 21.23% to 23.12% after the introduction of oleamide. Compared with the control and oleamide-modified devices, the deep-level defects were reduced by about five orders of magnitude due to the Lewis-base nature of amide groups in oleamide. In addition, due to the aggregation distribution of excess PbI 2 at GBs and the hydrophobicity of oleamide, the modified device showed better stability, maintaining 83% of its initial performance after 1000 h in air. [ABSTRACT FROM AUTHOR]

• A simple solvent engineering strategy was employed to control morphology of PbI 2 films effectively by water processing. • Platelet-like PbI 2 films can successfully control the residual amount of PbI 2 in perovskite film. • Platelet-like PbI 2 films can control the morphology of the perovskite film and improve the device efficiency [Display omitted] The performance of organic-inorganic perovskite solar cells depends largely on the quality of perovskite film. Currently, various methods are applied to prepare the perovskite film. Among them, the two-step method is counted as a promising candidate to obtain high-quality perovskite film. In this study, we attain a special platelet-like PbI 2 films by applying pure water to cover wet PbI 2 film and standing for a period of time. The unique morphology contributes to the entry of organic cations solution into the PbI 2 and promoting its reaction with PbI 2 , which reducing the residual amount of PbI 2 in the perovskite film. Compared to the traditional two-step method, water processing method can obtain a high-quality perovskite film with enlarged grain size, improved crystallization, and prolonged carrier lifetime. As a result, the efficiency of the prepared device based on the film has increased from 17.90% without water processing to 20.14% of water processing. Which demonstrates that this solvent engineering for PbI 2 film opens up a possibility to prepare high-quality perovskite in a two-step method and obtain highly efficient perovskite solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Fe3O4 magnetic nanoparticles (mean size of about 10nm) capped by surfactant oleic acid (OA) were incorporated into P3HT:PCBM BHJ-PSCs by doping in the P3HT:PCBM photoactive layer for the first time. The PCE of the OA-Fe3O4:P3HT:PCBM BHJ-PSC device is enhanced by ∼18% at the optimum OA-Fe3O4 NPs doping ratio of 1%. The role of the magnetic property of Fe3O4 NPs on the PCE of OA-Fe3O4:P3HT:PCBM devices was studied, confirming the exclusive contribution of the Fe3O4 NPs to the observed enhancement of PCE. The enhancement of the PCE of the OA-Fe3O4:P3HT:PCBM BHJ-PSC device is found to be primarily due to the increase of short-circuit current (J sc) by ∼14%, which is attributed to the magnetic field effect originated from the superparamagnetism of Fe3O4 NPs, resulting in the increase of the population of triplet excitons. Finally, the effect of Fe3O4 NPs on the enhancement of PCE of OA-Fe3O4:P3HT:PCBM device is further investigated by comparing different means of doping in P3HT:PCBM or PEDOT:PSS layer, confirming that such an effect can be achieved only when Fe3O4 NPs are doped in the P3HT:PCBM photoactive layer. [Copyright &y& Elsevier]

Gas-quenching fabrication of perovskite films demonstrates promising compatibility for commercialization of perovskite photovoltaics. Seeking suitable ligand for the perovskite precursor inks to improve the crystalline quality of gas-quenched methylammonium free perovskite films is critical for realizing up-scalable fabrication of stable perovskite solar cells. In this work, a series of pyrrolidone-based ligands are employed in gas-quenching fabrication of FA 0.9 Cs 0.1 PbI 3 perovskite films. Optical and morphological characterizations indicate 2-pyrrolidone is the most preferred ligand to deliver a neat buried-interface as well as a light-trapping surface at the rear of the device, which maximized the light-harvesting and the photocurrent of the device. The corresponding device achieved a power conversion efficiency of 21.6% without any interfacial passivation, as well as reduced defect density from their electrical characteristics. Moreover, a more stable performance of the device is obtained with 2-pyrrolidone compared to other pyrrolidone-based ligands, demonstrating 2-pyrrolidone as a promising ligand in designing the perovskite inks for methylammonium-free perovskite solar cells. • Various pyrrolidone-based ligands are studied in gas-quenching of FA 0.9 Cs 0.1 PbI 3 films. • Bifacial optical properties of perovskite films are optimized with NP ligand. • smoother buried interface and a rougher surface contribute to enhanced light harvesting. • NP device achieved 21.6% efficiency without any interfacial passivation [ABSTRACT FROM AUTHOR]

• Ti/Cr/Mo multiple layers improve thermal budget of the substrate. • High quality Cu(In,Ga)Se 2 film is obtained by a 2-step annealing process. • High temperature treatment improve the conversion efficiency of cells. In this work, we report the fabrication method using a Cu(In,Ga)Se 2 (CIGS) quaternary target containing NaF to obtain thin-film solar-cell devices on polyimide (PI) foils. In order to improve the efficiency of the CIGS solar cells, multiple metal layers were prepared on both sides of the PI substrate, and the annealing process was investigated. The sandwich structure of Ti/Cr/Mo multiple layers prepared on PI foils can improve thermal budget of the substrate as it endures higher annealing temperature (520 °C) for short time (5 min). A 2-step annealing process was adopted to ensure the integrity and fewer electrical defects of the absorber film. The distribution of Na and Ga elements in the annealed films was improved by adding a high-temperature selenization process. CIGS cells with better conversion efficiency can be obtained by this fabrication process. An average power conversion efficiency of 13.6% has been achieved for the prepared cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel heterogeneous lead iodide, exhibiting two (0 0 1) interplanar distances of 6.9 Å and 9.0 Å, was constructed. • The heterogeneous structure can regulate the crystallization process of PbI 2 and perovskite films. • The V OC and PCE were raised to 1.21 V and 24.24%. At present, the highest power conversion efficiency (PCE) of perovskite solar cells (PSCs) has exceeded 25%, which exhibits great potential for commercial applications. Obtaining pinhole-free, superior crystal, and high-quality perovskite films with fewer defects by adjusting the lead iodide (PbI 2) intermediate films in a two-step sequential deposition has become research arousing general interest. Herein, a heterogeneous lead iodide (HLI) structure with two (0 0 1) interplanar distances (9.0 Å and 6.9 Å), can optimize the crystallization process of perovskite to get better surface morphology and is constructed by intercalated choline chloride (a kind of vitamin B4, VB4). HLI simultaneously improves the carrier lifetime of perovskite film from 1.96 µs to 3.28 µs and reduces defect state density. Together with better morphology and lower defect state density, the open circuit voltage (V OC) and PCE based on (FAPbI 3) 0.97 (MAPbBr 3) 0.03 is significantly boosted. In addition, with double-sided modification, HLI produces an excellent PCE of 24.27% with a V OC of 1.21 V. We believe that the novel heterogeneous PbI 2 structure could be a generic method to improve the efficiency of PSCs. [ABSTRACT FROM AUTHOR]

Lead halide perovskite solar cells (PSCs) have attracted intensive attention since their power conversion efficiency (PCE) increased sharply in recent years. Thereinto, triple cation perovskite (TCP) is a popular light absorption layer for PSCs due to its excellent thermal and humidity stability. However, a large amount of MA+ (≥15%) and Br- (≥15%) in TCP makes the bandgap widen drifting from the optimum value. There is some extent of a trade-off between PCE and stability for PSCs, and narrow-bandgap TCP is one of the best choices for light absorption material to achieve an optimum balance between PCE and stability. Herein, we prepared a narrow-bandgap (1.56 eV) high-quality TCP (Cs 0.05 FA 0.86 MA 0.09 Pb(I 0.97 Br 0.03) 3) film with an average grain size up to 1208 nm and corresponding PSC with high efficiency of 20.8%. Moreover, the intermediate process of the TCP film crystallization was carefully studied disclosing the critical α-Phase intermediate and corresponding roles of DMSO solvent and MACl additive through quasi-in-situ XRD in the film formation process, and the results may give critical clues to the fabrication of high-quality narrow-bandgap TCP based PSCs. • High-quality FAPbI3-based TCP film with a narrow-bandgap (1.56 eV) was successfully prepared by applying the α-phase intermediate strategy: the grain size of the film can reach 1208 nm and the carrier lifetime exceeds 3 μs. • The crytical intermediate process introduced by the synergy of DMSO and MACl was disclosed through quasi-in-situ XRD in the film formation process. • The solar cells based on the low-doping FAPbI 3 -based TCP films show high performance and good stability even without surface passivation. [ABSTRACT FROM AUTHOR]

There has been extensive investigation into phase orientation and phase distribution for improving charge transfer in 2D perovskites-based PSCs, but very few reports have focused on the enhancement of inter-phase charge transfer by passivation. In this work, a synergetic strategy is developed by introducing hydrochloric acid and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) as additives to modulate phase distribution and passivate defects in (BA) 2 (FA) n−1 Pb n I 3n+1 (n = 9) quasi-2D perovskite films. In this process, perovskite films with suppressed phase segregation and PCBM molecules coated along the grain boundaries are obtained. PCBM is found to reduce the trap density by compensating defects, which accelerate inter-phase charge transfer and restrain nonradiative recombination, resulting in improved performance of quasi-2D PSCs. As a consequence, a high PCE of 15.01% with negligible hysteresis for quasi-2D PSCs is achieved. A synergetic strategy of phase distribution control and grain boundary passivation is developed for quasi-2D perovskite solar cells. The incorporation of PCBM into quasi-2D perovskite films with uniform phase distribution improves carrier lifetime and accelerates carrier extraction, resulting in an enhanced PCE. [Display omitted] • PCBM additive modifies the anti-solvent-assisted one-step process to fabricate the quasi-2D PSCs. • Inter-phase charge transfer is improved by the cooperation of optimised concentration of PCBM. • PCE is enhanced and hysteresis is eliminated for the devices with optimised PCBM incorporation. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was doped by 3-(Cyclohexylamino)-2-hydroxy-1-propanesulfonic acid (CAPSO), leading to dramatic improvement of its conductivity and consequently efficiency enhancement in inverted perovskite solar cells (PSCs) based on PEDOT:PSS hole transport layer (HTL). Under the optimized CAPSO doping concentration, the conductivity of PEDOT:PSS film increased by about three orders of magnitude, and this is interpreted by the weakening of the coulombic attractions between PEDOT and PSS components induced by CAPSO. CAPSO doped PEDOT:PSS (PEDOT:PSS@CAPSO) was applied as HTL of PSCs devices based on CH 3 NH 3 PbI 3 layers, leading to the best power conversion efficiency (PCE) of ~38% enhanced relative to those of the corresponding reference devices based on pristine PEDOT:PSS HTL. Scanning Kelvin probe microscopy (SKPM) results show that the work function of PEDOT@CAPSO matches well with the valence band of CH 3 NH 3 PbI 3 absorbers. The research demonstrates that the zwitterion modified PEDOT:PSS could act as an outstanding hole transport material for fabricating high-efficient perovskite solar cells. A new zwitterion, 3-(Cyclohexylamino)-2-hydroxy-1-propanesulfonic acid (CAPSO), induced to dope PEDOT:PSS, leading to a dramatic increase of the conductivity of PEDOT:PSS film. PEDOT:PSS@CAPSO was incorporated as hole transport layer (HTL) in inverted perovskite solar cells devices based on CH3NH3PbI3, resulting in obvious efficiency enhancements, which is attributed to the conjunct factors including the increase of the crystallinity of perovskite layer and the improved conductivity of PEDOT:PSS HTL. Image 1 • A new zwitterion, CAPSO, introduced to dope PEDOT:PSS, leading to a dramatic increase of the conductivity of PEDOT:PSS film. • PEDOT:PSS@CAPSO was incorporated as hole transport layer (HTL) in inverted perovskite solar cells based on CH 3 NH 3 PbI 3. • Modified PEDOT:PSS HTL induced obvious efficiency enhancement for inverted perovskite solar cells. • Improved efficiency is due to the increased crystallinity of perovskite layer and improved conductivity of PEDOT:PSS HTL. [ABSTRACT FROM AUTHOR]