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Interfacial modification of the perovskite surface with octocrylene (2-ethylhexyl-2-cyano-3,3-diphenyl-2-propenoate, OCT) is capable of enhancing humidity stability and passivating the defects of perovskite films. In this study, octocrylene can be attached to the surface of the perovskite, and the carbonyl group (C＝O) in octocrylene achieved excellent passivation through the Lewis base electron passivation of Pb2+ ions. By increasing the concentration of the octocrylene/IPA solution, the modified device exhibited an optimal PCE of 20.54% and a steady state output PCE of 19.75%. This study shows that the introduction of octocrylene in the preparation of perovskite could effectively enhance the performance of perovskite solar cells. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL) between the perovskite material and cathode plays an important role in planar perovskite solar cells. In this study, an alkali metal salt solution was be used to modify the surface of the SnO2 electron transport layer to optimize electron transport. The I–V characteristic measurements and UV-Vis spectroscopy were used to investigate whether introducing the interface modification can increase the electron coupling and effectively extract the energy lever of electrons. The results indicated that the interfacial modification could reduce the trap density of states and increase the mobility of the SnO2 thin films. The efficient defect passivation significantly suppressed the recombination at the SnO2/perovskite interface. This method aims at passivation using simple and low-cost inorganic material poles. [ABSTRACT FROM AUTHOR]

It is well known that the different proportions of CuO and Cu2O in CuOx hole transfer materials have a great influence on the hole transport property as well as the device performances of perovskite solar cells (PSCs). In this paper, we changed the content of Cu2O in the film by controlling the deposition voltage during electrodeposition, and the effects of different contents of Cu2O in the films on the device were investigated for the first time. It was found that the content of Cu2O in the film reached the highest point with the deposition voltage 0.5 V, such films have the highest transmittance and carrier mobility. After assembling the device, the power conversion efficiency (PCE) of the champion device reached 13.48% under a one-sun AM 1.5 G (100 mW/cm 2) illumination. Furthermore, the unpackaged device based on CuOx still retained over 75% PCE after being placed in the ambient condition (30–40% humidity, 20–30 ∘ C) for 500 h. The content of Cu+ in the deposited film was controlled by changing the electrodeposition voltage. The content of Cu+ in the film reached the highest at a deposition voltage of 0.5 V. At the same time, the properties such as transmittance, carrier mobility and electrical conductivity of the film were optimized, and the PCE of the device was the highest. [ABSTRACT FROM AUTHOR]

CZTS has been considered to be a perfect suitable replacement for CuInGaSe 2 (CIGS) which contains the rare elements. This work developed a novel route to fabricate CZTS absorber films based on the integration of non-vacuum and vacuum techniques. This was illustrated by first synthesizing CZTS powder with the method of solid-phase synthesis. Then three different compound targets made of CZTS precursors and pure CZTS powder were utilized to fabricate CZTS absorber films using Radio Frequency (RF) sputtering, followed by a sulfurization process. All synthesized samples were analyzed with respect to their crystal structure, vibrational property, morphology and chemical composition. The photoelectrical properties investigation of the sulfurized absorber films by UV-VIS spectrophotometer and Hall effect measurement can well meet the requirements for potential application in thin film solar cells, demonstrating this approach had great potential for CZTS solar cell production. [ABSTRACT FROM AUTHOR]

CZTSSe is an important earth abundant collection of materials for the development of low cost and high efficiency thin film solar cells. This work developed a simple non-vacuum-based route to fabricate CZTSSe absorber films. This was demonstrated by first synthesizing Cu 2 ZnSnS 4 (CZTS) nano-crystalline based on solid-phase synthesis. Then a stable colloidal ink composed of CZTS nano-crystalline was blade coated on Mo-coated substrates followed by an annealing process under Ar atmosphere. After CZTS films formation, the films were sintered into CZTSSe absorber films by exposing them under Selenium vapor. The formation of a kesterite type CZTS was confirmed using X-ray diffraction and Raman scattering measurements. The band gap of CZTSSe absorber films was determined to be 1.26 eV, which was appropriate for use as an absorber layer in thin film solar cells. The CZTSSe absorber films showed a good photovoltatic performance, demonstrating this simple approach had great potential for CZTSSe solar cell production. [ABSTRACT FROM AUTHOR]

Abstract: ZnO:Al thin films were deposited on glass substrates by RF magnetron sputtering from a powder compacted ceramic target. Structural, electrical and optical properties of the films with different thickness were characterized. The damp heat stability of ZnO:Al thin film was investigated for its application in thin-film solar cells. After the 1000h damp heat treatment in harsh conditions of 85% relative humidity at 85°C for all samples, a degradation of electrical properties was observed, while the transmissions of the films were almost unchanged. Thick films with a relative large grain size could form compact structure to resist the corrosion by oxygen and water molecules. [Copyright &y& Elsevier]

In the two-step spin-coating method, the crystallization and morphology of PbI 2 film are essential for producing highly efficient and stable planar heterojunction (PHJ) perovskite solar cells. In this work, the dithizone (DTZ) molecules were introduced into PbI 2 precursor to improve the performance of perovskite films. We found that adding DTZ was an effective method to retard the crystallization of PbI 2 film and consequently, produced a high-quality perovskite film with pinhole-free, smoother, and fewer defects surface. Most importantly, the presence of residual DTZ in wet PbI 2 film also assisted DMSO to slow down the growth of perovskite grains. By tuning the concentration of DTZ, the power conversion efficiency of the best performed cell has increased to 20.66% with negligible photocurrent hysteresis. Meanwhile, the best DTZ device offer an excellent stability, which retained 97% of the initial PCE after storage in the dark for approximately 24 days. We expect this controlled crystallization method could be further explored and provides a useful strategy to improve the performance of perovskite solar cells. • Dithizone was firstly applied to the planar heterojunction perovskite solar cells. • The dithizone film could retard the crystallization of PbI 2 and assist DMSO to slow down the nucleation of perovskite. • The best performed device with DTZ-1 showed PCE of 20.66% and high stability. [ABSTRACT FROM AUTHOR]

Currently, tin oxide (SnO2) is a highly sought-after semiconductor material used in perovskite solar cells (PSCs) because of its good transmittance, the appropriate energy level, high electron mobility, high conductivity, ideal band gap and excellent chemical stability. In this study, SnO2 film was successfully prepared by radio frequency reactive magnetron sputtering (RS) under room temperature conditions. The obtained SnO2 thin films not only exhibited high transmittance in the visible region as well as the pure phase, but also had a suitable energy band structure and lower surface roughness than FTO (SnO2:F) glass substrate, which contributes to the improvement of the adjacent interface morphology. The SnO2 films prepared by reactive sputtering could effectively suppress carrier recombination and act as an electron transport layer. Moreover, the maximum efficiency of the device based on reactive sputtering of SnO2 as the electron transport layer (ETL) for planar perovskite solar cells (PSCs) was 14.63%. This study mainly described the preparation of SnO2 by reactive sputtering under room temperature conditions. [ABSTRACT FROM AUTHOR]

Interfacial engineering has been widely recognized as among the most effective approaches to deriving high performance perovskite solar cells (PSCs). [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 BM) and silver (Ag) were extensively used as the electron transport material and cathode material in the inverted device. However, the energy level mismatch between PC 61 BM and Ag cathode has a possibility to severely affect the electron extraction and transportation. Hereby, only alcohol-soluble carbon dots (CDs) were synthesized and applied as a cathode interlayer (CIL) through a simple solution-process to make alteration to the interface between PC 61 BM and Ag in inverted PSCs, the PC 61 BM/CDs layer was generated with low trap-state density, high electrical conductivity, high electron mobility and appropriate energy level. Finally, the inverted device with the CDs CIL exhibited a power conversion efficiency (PCE) of 17.34% with the steady-state output PCE reaching 16.96%. The stability of devices was also enhanced due to the hydrophobicity of the CDs cathode interlayer. The efficiency of inverted PSCs with PC 61 BM/CDs layer remained 70% of the initial PCE under dry condition after 40 days versus only 20% of the initial PCE for the PCBM ETL without CDs. Image 1 • Only alcohol-soluble carbon dots (CDs) were synthesized and applied as a cathode interlayer (CIL). • The energy level mismatch between PC61BM and Ag cathode was improved. • Electrical conductivity and trap-state density were tested. • The performance and stability of the device with CDs was enhanced. [ABSTRACT FROM AUTHOR]

• Hexadecyl trimethyl ammonium Bromide was introduced into PEDOT:PSS. • The work function of PEDOT:PSS was tuned from −4.18 to −4.21 eV. • The PCE of the device was improved from 10.21% to 12.53% with the V oc increased. • The long-term stability of the device with CTAB has been modified. The power conversion efficiency (PCE) reported for the inverted perovskite solar cells (PSCs) is still less than that of the regular structure, and low open circuit voltage (V oc) is one of the crucial problems for achieving high PCE in inverted PSCs. In this study, a new modification strategy was developed by doping poly (3,4-ethylenedioxythiophene)-poly-(styrene sulfonate) (PEDOT: PSS) with the cetyl trimethyl ammonium bromide (CTAB) to passivate the bottom of perovskite layer and enhance properties of PEDOT:PSS. The work function of PEDOT: PSS was altered from −4.18 to −4.21 eV, the Fermi level of CTAB-doped PEDOT:PSS better fitted to the valence band of perovskite layer, thereby leading to a higher build-in voltage. As a result, the V oc increased by 70 mV, up to 0.90 V and the PCE of the device increased from 10.21% to 12.53%. Furthermore, the device based on CTAB-doped PEDOT:PSS still retained over 75% of the initial PCE after exposing the device in the ambient condition (20–40% humidity, 10–30 ℃) for 30 days. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we introduce several kinds of volatile anti-solvents to prepare a fully-reacted perovskite film, thereby obtaining a high-efficiency solar cell. The volatility of the solvent strongly influences the uniformity and porosity of the PbI 2 film, and thus affects the uniformity and compactness of the obtained perovskite film. Scanning electron microscopy (SEM) revealed that the perovskite film fabricated by the ethanol treatment method was very dense and exhibited a smoother surface. At the same time, the compositions of the perovskite films produced using different volatile solvents were determined via X-ray diffraction (XRD), and it was found that the film fabricated by the ethanol treatment method completely reacted with no residual PbI 2. The ethanol treated sample was characterized by UV–vis spectroscopy and current density-voltage (J-V) measurements, and the best absorbance, a fill factor of 0.73, short circuit current density, J sc , of 22.1 mA cm-2, an open circuit voltage, V oc , of 1.04 V and a photoelectric conversion efficiency, PCE, of 16.8% were obtained. Graphical abstract Image 1 Highlights • Conventional method produces residual PbI 2. • Residual PbI 2 deteriorates solar cell photoelectric performance. • Ethanol removes residual PbI 2. [ABSTRACT FROM AUTHOR]

At present, SnO 2 is a widely used material for the electron transport layer in n-i-p perovskite solar cells. However, the SnO 2 films prepared by the spin-coating method inevitably generate many defects, especially at the interface. Many strategies have been proposed to passivate the defects of the upper SnO 2 interface, but relatively few studies on the SnO 2 buried interface. In this study, we introduced thiourea molecules into the SnO 2 buried interface. The bottom-up diffusion can effectively passivate the uncoordinated Sn4+ and oxygen vacancies in SnO 2 film, benefiting from the passivation of two –NH 2 and S atoms with lone pair electrons. In addition, by comparing the different characteristics of SnO 2 buried interface modification and the SnO 2 doping with thiourea, the two strategies were combined, and the thiourea showed a better passivating effect under this co-processing strategy. Compared with the Control device (19.74 %), the device under the co-processing strategy at the optimal concentration exhibits better photovoltaic performance and stability, which obtained the photoelectric conversion efficiency of 21.09 % and remained at 88.2 % of the initial efficiency after being aged in the air for 60 days without encapsulation. The co-processing strategy provides a valuable reference for the defect passivation of the SnO 2 film and its buried interface. [Display omitted] • Thiourea was introduced into the SnO 2 buried interface for the first time. • Thiourea showed a better passivating effect under a co-processing strategy. • The co-processing strategy greatly improves the performance of PSCs. [ABSTRACT FROM AUTHOR]

The presence of defects in the perovskite absorption layer significantly reduces the photovoltaic performance of perovskite solar cells (PSCs). In this study, a Lewis base Triethanolamine (TEA) is introduced on the perovskite surface, and the hydrogen bond formed by its hydroxyl group with Pb ions or I ions fix the halogen anion of perovskite and suppresses the migration of ions in perovskite. TEA has an obvious effect at the grain boundary, significantly improving the surface quality of the perovskite film and the device's efficiency. Compared with the pristine device (19.26%), the device after passivation at the optimal concentration exhibits better photovoltaic performance and stability, which obtained the champion efficiency of 20.39% and remained at 88.3% of the initial efficiency after being aged 1080 h without encapsulation. We expect that adding TEA to the perovskite surface will provide a useful strategy to enhance the performance of PSCs, as well as air and thermal stability. [Display omitted] • Triethanolamine was introduced as a perovskite passivator for the first time. • Triethanolamine effectively improved the morphology of perovskite and passivated the surface defects. • Triethanolamine significantly improves the thermal stability of the device. [ABSTRACT FROM AUTHOR]

Abstract CuO x has attracted more attention as a hole transport material. Electrochemical deposition is a simple and efficient coating method, which avoids high temperature process, complicated operation and avoided material waste during coating process. The ultrathin CuO x films were fabricated in CuSO 4 and lactic acid mixed liquids through a simple electrochemical deposition method. The CuO x thin films prepared at pH = 9 showed the best conductivity and light transmittance. After the optimization of the devices, the performance of the device shows a best power conversion efficiency (PCE) of 13.48% under standard AM 1.5G simulated solar irradiation with a shadow mask of 0.1cm2 and remained over 75% PCE after storing for 500 h. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Highlights • we used urea as a novel additive in synergy with DMSO forming a smooth, large grain-size perovskite film. • The use of urea can significantly increase the short-circuit current of perovskite solar cells. • Adding slight amount of DMSO aimed at improving the reproducibility of device and optimizing the spin-coating process. Abstract Perovskite solar cell has gained wide attention due to its excellent photoelectric performance and economical fabrication process, with high-efficiency perovskite solar cell could be achieved by optimizing film morphology. In this work, a kind of Lewis-bases, urea(U), was used as a novel additive in synergy with DMSO to regulate the crystallization processes. Adding slight amount of DMSO can obviously improve the reproducibility of device and optimize the spin-coating process. The mechanism of the action can be explained by infrared spectroscopy. Under the coordination of the lead ion that could accept electron pairs and the C O bond in urea, introduction of urea in perovskite precursor solution to form MAI·PbI 2 ·DMSO·urea complex could significantly improve the photoelectric properties of the perovskite films. It formed a smooth and large grain-size perovskite film with no visible pinhole or crack found. Finally, the device fabricated with the incorporation of 50% urea presented a high performance with a PCE of 17.82%. [ABSTRACT FROM AUTHOR]

Highlights • Large guanidinium cation was utilized to treat the surface of MAPbI 3 films. • Perovskite solar cells have been prepared based on solution-processed secondary growth technique. • The presence of Gua molecules at the interfaceincreases all photovoltaic properties, in particular V oc. • The more n-type (Gua 1−x MA x)PbI 3 perovskite film was obtained to enhance the performance of the device. Abstract Recently, perovskite solar cells (PSCs) have been rapidly developed, counting as the most promising alternative to the Si solar cells, but non-radiative charge carrier recombination at grain boundaries limited open circuit voltages and consequent performance improvements of perovskite solar cells. In this work, a new perovskite film growth method was presented here using the organic molecule guanidinium (CH 6 N 3 +, Gua) to assist the secondary growth after the formation of perovskite films. It is found that the presence of Gua molecules at the interface between the perovskite film and the hole conductor layer increases all photovoltaic properties, in particular V oc as well as the operational stability of the PSCs. The optimum performance of the planar perovskite solar cells demonstrated a PCE of 18.54% with a higher V oc of 1.10 V and potent stability for 30 days in dark under dry condition. These results presented a simple method for suppressing non-radiative charge carrier loss in hybrid perovskite solar cells to further enhance the device performance toward highly efficient solar cells. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) as the most promising alternative to the Si solar cells have been developed rapidly in recent time. Superior electron mobility and conductivity of the compact layer material are necessary for high efficiency in perovskite solar cells by reducing excessive charge accumulation and guaranteeing effective electron injection at the compact layer/perovskite interface. In this study, Ru ions were introduced into traditional compact TiO 2 to improve the electron transporting layer (ETL) properties and conductivity performance. Ru 4+ was discovered in the Ru:TiO 2 according to the result of XPS. The reduced trap-filled limit voltage (V TFL ) of the Ru:TiO 2 compact layers showed that trap density in the Ru:TiO 2 film was lower than that of the pristine TiO 2 film. The PSCs based on 1 mol% Ru:TiO 2 exhibited the suitable band gap, low resistivity and high carrier density, comparing with the undoped compact TiO 2 , the charge transportation at the compact layer/mesoporous layer interface was enhanced with the incorporation of Ru, resulting in the reduction in hysteresis of the device. The power conversion efficiency (PCE) of the Ru-doped compact TiO 2 film based PSCs was improved from 14.83% to 18.35%. [ABSTRACT FROM AUTHOR]

Carbon electrodes represent a promising strategy for creating stable and low-cost perovskite solar cells (PSCs). However, PSCs with carbon electrodes usually suffer from energy level mismatch at the perovskite/carbon interface. In this study, the application of cetyltrimethylammonium bromide (CTABr) as a self-assembled monolayer (SAM) is explored to optimize the energy level alignment. As a result, CTABr-modified cell shows a 22.26% improvement in power conversion efficiency (PCE) and delivers an impressive PCE of 11.26% with a stabilized current density of 15.59 mA/cm2. Moreover, in a damp environment (humidity ≈85%) without encapsulation, CTABr-modified PSCs remain at 90% and 57% of the initial efficiency after being aged for 240 and 480 h, respectively. This study paves a new route for preparing better-performing PSCs with carbon using a low-temperature process. [Display omitted] • CTABr is explored to optimize the energy level alignment at the perovskite/carbon interface. • The champion cell delivers an PCE of 11.26% with a stabilized current density of 15.59 mA/cm2. • CTABr-modified cell shows a 22.26% improvement in energy conversion efficiency compared to the cell without modification. • CTABr-modified PSCs remain 90% of the initial PCE value after 240 h under 85% humidity without encapsulation. [ABSTRACT FROM AUTHOR]

• Using Li-doped SnO 2 (Li:SnO 2) as an effective ETL, improve the electrical properties of SnO 2. • Solar devices are fabricated by a facile two-step deposition strategy. • Optimized equipment improved V oc , FF and J sc. Got a device with a maximum PCE close to 19%. SnO 2 has recently aroused huge attention as an electron transfer material for planar halide perovskite solar cells. Nevertheless, planar structure devices exhibit significant hysteresis behavior and low optical stability for their considerable trap states and high ultraviolet transmittance. In this study, LiCl was added to the SnO 2 electron transport layer. As revealed from the results, adding LiCl could enhance the mobility of SnO 2 film and promote the optical stability. Lastly, Li:SnO 2 devices achieved high power conversion efficiency (PCE) of over 18% and steady-state PCE of 18.35%. Besides, they displayed prominent stability storage under dry conditions. [ABSTRACT FROM AUTHOR]

Inverted perovskite solar cells with NiO x hole transport layer (HTL) have attracted abundant attention due to low-cost fabrication and high device-efficiency. However, the further development of NiO x -based inverted perovskite solar cells (PSCs) would be restricted by the unsatisfactory electrical properties in pristine NiO x and the non-ideal charge transfer between perovskite and NiO x. In this work, a facile and effective method was designed to regulate the electronic property of NiO x HTL and make an alteration to the interface between the perovskite and NiO x. NH 4 F was used as an interfacial modifier to enhance the charge transfer between the perovskite layer and NiOx. The NiO x -F layer was generated with high transmittance and low trap density. Besides, the power conversion efficiency of the device was improved from 17.17% to 18.94% with the improvement of short-circuit current (J sc) by using the structure of ITO/NiO x /NH 4 F/MAPbI 3 /PCBM/BCP/Ag. Finally, the device with NH 4 F exhibited better stored stability in the dry condition compared with the control device. Image 1 • NH 4 F solution was utilized to treat the surface of NiOx films. • The electronic properties of the NiOx films were improved. • The introduction of NH 4 F improves the performance of the device, in particular Jsc. • The device with NH4F exhibited better stored stability in the dry condition. [ABSTRACT FROM AUTHOR]