Search

The surfaces of perovskite films are vulnerable to the moisture in the surroundings, and surface passivation is a widely accessible technique to solve this problem. Here, we report an effective strategy to improve the stability and photovoltaic performance of MAPbI3 perovskite solar cells by surface passivation with Naphthylmethylamine (NMA). The solar cell devices without NMA showed a highest power conversion efficiency (PCE) of 18.4%, while the devices with NMA achieved a highest PCE of 19.4% under the same conditions. The reduced trap density and enhanced recombination resistance are thought to be the main reasons for the improved photovoltaic performance. Moreover, the long-term stability of the passivated solar cell devices was also greatly enhanced. The NMA-treated device maintained 90% of its original PCE after 90 days storage at a relative humidity of 60% and 25 °C, while the device without NMA only maintained 72% of its original PCE under the same conditions.

Due to their excellent photoelectron chemical properties and suitable energy level alignment with perovskite, perylene diimide (PDI) derivatives are competitive non-fullerene electron transport material (ETM) candidates for perovskite solar cells (PSCs). However, the conjugated rigid plane structure of PDI units result in PDI-based ETMs tending to form large aggregates, limiting their application and photovoltaic performance. In this study, to restrict aggregation and further enhance the photovoltaic performance of PDI-type ETMs, two PDI-based ETMs, termed PDO-PDI2 (dimer) and PDO-PDI3 (trimer), were constructed by introducing a phenothiazine 5,5-dioxide (PDO) core building block. The research manifests that the optoelectronic properties and film formation property of PDO-PDI2 and PDO-PDI3 were deeply affected by the molecular spatial configuration. Applied in PSCs, PDO-PDI3 with three-dimensional spiral molecular structure, exhibits superior electron extraction and transport properties, further achieving the best PCE of 18.72% and maintaining 93% of its initial efficiency after a 720-h aging test under ambient conditions.

Redox mediators play a major role in determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Copper complexes are a good option for redox mediators but suffer from elec...

A new crosslinked polymer, called P65, with appropriate photo-electrochemical, opto-electronic, and thermal properties, has been designed and synthesized as an efficient, dopant-free, hole-transpor ...

Low cost N-bromosuccinimide (NBS) was applied as an effective p-type dopant in 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (Spiro-OMeTAD), an important hole transport material (HTM) for perovskite solar cells (PSCs). At the optimum doping concentration, the hole mobility, conductivity, stability, and various performances of the devices were significantly improved, particularly the hole mobility increased by more than 3.5 times from 1.39 × 10−4 cm2 V−1 s−1 to 4.92 × 10−4 cm2 V−1 s−1. This dopant prompted the power conversion efficiency (PCE) of the PSC device from 16.12% to 19.24% (0.1 cm2, AM 1.5G, 100 mW cm−2) with high stability.

Molecularly engineered strongly conjugated and rigid hybrid triazatruxene (TAT)-based dyes ZL001 and ZL003 were fabricated as excellent dyes for solid-state dye sensitized solar cells (ssDSSC). Y123 was used as a reference dye. The efficiencies of 5.4%, 6.6% and 6.1% for ZL001, ZL003 and Y123 based solid-state devices are obtained, respectively, with 2,2′,7,7′-tetrakis (N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) as hole transporting material. The photovoltaic performance of the TAT-based dye ZL003 was higher than previously published Y123 dye, which possesses a strong push pull conjugated structure. The effects of molecular structure on optical and electrochemical properties, charge extraction kinetics, and photovoltaic performance of the sensitizers were systematically researched. Our results indicate that TAT-based dyes are attractive for application in ssDSSC.

Recently, it has become highly desirable to develop low-cost, dopant-free, hole-transport materials with a high charge mobility for perovskite solar cells. Herein, by using an electron deficient be...

Three novel dyes consisting of a 5,8,15-tris(2-ethylhexyl)-8,15-dihydro-5H-benzo[1,2-b:3,4-b':6,5-b″]tricarbazole (BTC) electron-donating group and a 4,7-bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (BTBT) π-bridge with an anchoring group of phenyl carboxyl acid were synthesized and applied in dye-sensitized solar cells (DSCs).The AJ202 did not contain any triple bonds, the AJ201's ethynyl group was inserted between the BTC and BTBT units, and the AJ206's ethynyl group was introduced between the BTBT moiety and the anchor group. The inclusion and position of the ethynyl linkage in the sensitizer molecules significantly altered the electrochemical properties of these dyes, which can fine-tune the energy levels of the dyes. The best performing devices contained AJ206 as a sensitizer and a Cu(I/II) redox couple, which resulted in a power conversion efficiency (PCE) up to 10.8% under the standard AM 1.5 G illumination, which obtained PCEs higher than those from the devices that contained AJ201 (9.2%) and AJ202 (9.7%) under the same conditions. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the sensitizers were tuned to be well-suited for the Cu(I/II) redox potential and the Fermi level of TiO2. The innovative synthesis of a tricarbazole-based donor moiety in a sensitizer used in combination with a Cu(I/II) redox couple has resulted in relatively high PCEs.

All-inorganic cesium lead bromide (CsPbBr3) perovskite is attracting growing interest as functional materials in photovoltaics and other optoelectronic devices due to its superb stability. However, the fabrication of high-quality CsPbBr3 films still remains a big challenge by solution-process because of the low solubility of the cesium precursor in common solvents. Herein, we report a facile solution-processed approach to prepare high-quality CsPbBr3 perovskite films via a two-step spin-coating method, in which the CsBr methanol/H2O mixed solvent solution is spin-coated onto the lead bromide films, followed by an isopropanol-assisted post-treatment to regulate the crystallization process and to control the film morphology. In this fashion, dense and uniform CsPbBr3 films are obtained consisting of large crystalline domains with sizes up to microns and low defect density. The effectiveness of the resulting CsPbBr3 films is further examined in perovskite solar cells (PSCs) with a simplified planar architecture of fluorine‒doped tin oxide/compact TiO2/CsPbBr3/carbon, which deliver a maximum power conversion efficiency of 8.11% together with excellent thermal and humidity stability. The present work offers a simple and effective strategy in fabrication of high-quality CsPbBr3 films for efficient and stable PSCs as well as other optoelectronic devices.

Two-dimensional Ruddlesden-Popper perovskites (2D-RPPs) have attracted attention due to their superior moisture stability. In this study, we prepared and characterized a new group of 2D perovskites with cyclohexane methylamine (CMA+) as a spacer cation. The compounds (CMA)2(MA)n−1PbnI3n+1 (n = 1, 2, 3, and 4) showed high self-assembly (where MA is CH3NH3), which allowed for high-quality films to be deposited through the one-step spin-coating method in ambient air. Hot-casting technique, additives, and glove box were not required in the fabrication process. The bandgaps of this group of compounds can be varied from 2.36 eV for (CMA)2PbI4 (n = 1) to 1.52 eV for MAPbI3 (n = ∞) with increasing n value. Moreover, we found that the thin films of (CMA)2(MA)n−1PbnI3n+1 showed considerable stability in moisture and thermal tests. We successfully inserted these new 2D-RPPs in solar cells, and obtained the best power conversion efficiency of 10.66%, with an open-circuit voltage (Voc) of 1.00 V, and a short-circuit current density (Jsc) of 16.99 mA/cm2 for our first-generation device containing (CMA)2(MA)3Pb4I13 (n = 4). The CMA-based devices exhibited superior long-term stability, the unencapsulated (CMA)2(MA)3Pb4I13 solar cell retained nearly 95% of its initial efficiency when exposed to ambient conditions with a 60% relative humidity for 1500 h.

Low-cost poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have been widely used as hole-transporting materials (HTMs) in p–i–n perovskite solar cells (PSCs). However, reports on the use of PEDOT-based HTMs in regular PSCs have been rather limited up till now due to the low solubility of PEDOT in organic solvents. In this work, we report three PEDOT derivatives, namely, PEDOT-C6 (P6), PEDOT-C10 (P10), and PEDOT-C14 (P14), with a simple synthetic process by tailoring the length of the alkyl side-chains, and apply them as dopant-free HTMs in mesoscopic n–i–p structured PSCs. It is revealed that the alkyl side-chain length has a significant impact on the film morphology, hole transport capability, and thus the overall solar cell performance. The devices with P10 afford a champion PCE of 16.2% at one sun illumination (100 mW cm−2, AM 1.5G), which is significantly higher compared to those based on P6 (12.1%) and P14 (14.8%) under identical conditions. This has been the highest PCE reported so far for dopant-free PEDOT-based HTMs in conventional PSCs. The greatly enhanced photovoltaic performance observed for the P10-based devices is mainly attributed to the superior film formation property and hole transport capability of P10. Furthermore, the devices utilizing P10 also show excellent ambient stability, retaining 75% of their initial performance at a relative humidity (RH) of 80% after 120 h due to the high moisture resistivity of the HTM. The present work provides a new avenue for further developing low-cost, efficient, and stable HTMs in PSCs in the future.

Two push–pull metal-free sensitizers with 5,11-dihydroindolo[3,2-b]carbazole derivatives as electron-donating groups and 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid (BTZ) as electron-withdrawing unit, denoted by SK201 and SK202, were synthesized and used for fabrication of dye-sensitized solar cells (DSSCs). SK202 contains a thienyl group between the donor and acceptor, whereas in SK201 the donor and acceptor are connected directly by a single bond. Introduction of a thienyl group improved the planarity of the dye molecule, broadened the absorption spectrum, enhanced the molar extinction coefficient, increased the dye loading on TiO2, and accelerated interface electron transfer on TiO2. This fine tuning of dye structure improved the performances of DSSCs based on SK202 sensitizers and gave a power conversion efficiency (PCE) of 11.0% (Jsc 16.5 mA cm−2, Voc 932 mV, and fill factor 71.7%), compared with that of 7.2% for SK201, under standard AM1.5G solar irradiation (100 mW cm−2) with a Co(II/III) complex based redox couple.

Two dyes with dithieno[3,2-b:20,30-d] pyrrole (DTP) as the donor (An101 and An102) have been synthesized and characterized. An101 and An102 were applied to dye-sensitized solar cells (DSSCs) and power conversion efficiencies (PCEs) of 8.0% and 9.5% were achieved with the I2−/I3− redox couple, which correspond to open voltages (Voc) of 784 and 690 mV, current densities (Jsc) of 15.1 and 20.0 mA cm−2, the fill factors of 67.2% and 68.7%, respectively, under AM1.5G irradiation. It is worth noting that the different connection locations of the donors with the π-bridge result in different PCEs. An102 has a higher Jsc owing to its high molar extinction coefficient and small torsion angle, which increase the light-harvesting ability and coplanarity. An101 has a higher Voc owing to introduction of the alkoxybenzene group, which can effectively suppress recombination with the electrolyte and dye. By scanning with different bias voltages with electrochemical impedance spectroscopy, the reason for the high voltage of the An101 dye is up-shift of the TiO2 conduction-band edge and elongated electron lifetimes. However, the main reason for the relatively high PCE of the An102 dye is the coplanarity, which results in good long-term stability.

Two novel fluorene-based hole transporting materials (HTMs) were synthesized to be used in perovskite solar cells (PSCs). C102 was designed based on C101 by simply linking the two carbon–carbon single bonds to compose a “dispiro” structure. Their typically similar structures cause them sharing almost the same energy levels. However, their photovoltaic performances are quite different due to the small variations. The PSC that contained the “dispiro” structure, C102, reached a power conversion efficiency (PCE) of 17.4%, while the device contained C101, obtained a lower PCE of 15.5%. Electrochemical properties and Photovoltaic characterization of the two materials have been investigated to explain the result. It is shown that C102 has a stronger ability to transport holes and resist the charge recombination. Thus, the dispiro structure should be more appropriate being used as HTM in PSCs.

The electron-injection energy losses of dye-sensitized solar cells (DSSCs) are among the fundamental problems hindering their successful breakthrough application. Two triazatruxene (TAT)-based sensitizers, with one containing a flexible Z-type double bond and another a rigid single bond, coded as ZL001 and ZL003, respectively, have been synthesized and applied in DSSCs to probe the energy losses in the process of electron injection. Using time-resolved laser spectroscopic techniques in the kinetic study, ZL003 with the rigid single bond promotes much faster electron injection into the conductive band of TiO2 especially in the locally excited state (hot injection), which leads to higher electron density in TiO2 and a higher Voc. The devices based on ZL003 exhibited a champion power conversion efficiency (PCE) of 13.6% with Voc = 956 mV, Jsc = 20.73 mA cm–2, and FF = 68.5%, which are among the highest recorded results to date on single dye-sensitized DSSCs. An independent certified PCE of 12.4% has been obt...

This paper aims to develop high quality screen-printed Al emitters and improve the interface condition of rear contacts in industrial silicon solar cells. We propose to introduce an ultra-thin SiO2 buffer layer between the silicon bulk and metal contact during the fabrication process. A post-annealing strategy is adapted to further modify the Al doping profiles. The experimental results show that the effects of this oxide layer on migrating the nonuniformity of Al-p+ region and decreasing the defects at the metal–silicon interface are significant. The recombination velocity of contacts, which is extracted from the measured Srear by an analytical model, exhibits a decrease by 90.8% and the series resistance is reduced by 60.3% for the improved contacts compared to the conventional screen-printed contacts. Finally, this technique is applied to large-area (156 × 156 mm2) industrial n-type silicon solar cells and leads to a 2.18% increase in average cell efficiency, including a 12.82 mV increase in open-circuit voltage Voc and 0.99 mA cm−2 increase in short-circuit current density Jsc compared with solar cells fabricated by a standard industrial process. A 19.16% efficient cell with a Voc of 637.47 mV is achieved.

The development of facilely synthesized, dopant-free hole-transporting materials (HTMs) with high efficiency is of great significance for the potential application of perovskite solar cells (PSCs). Herein, we report two novel indolo[3,2-b]carbazole (ICZ) based small molecules obtained via a three-step reaction in a high yield without using expensive catalysts, namely C201 and C202, and further apply them as dopant-free HTMs in PSCs. Compared with C201, C202 contains two additional biphenylamino groups to improve its spatial configuration. It is found that the interplay between the molecular geometry and the aggregation behavior can exert a great influence on the film formation property and thus on the device performance. Strikingly, the champion devices employing C202 as the HTM deliver a much higher PCE of up to 17.7%, which is substantially higher than that of devices containing C201 (8.7%) under 100 mW cm−2 illumination (AM 1.5G). It is revealed that the C202 capping layer exhibits a more homogeneous and uniform surface morphology as compared to that of C201, which effectively reduces the charge recombination losses and facilitates charge extraction, leading to a much-enhanced photovoltaic performance. This is the first example of ICZ core-based small molecules as dopant-free HTMs in PSCs. Moreover, the PSCs containing C202 as the HTM also exhibited good long-term stability under ambient conditions (40% RH) as compared to devices with doped spiro-OMeTAD, due largely to the hydrophobic nature of C202 which prevented moisture from destroying the perovskite film. This work offers a new avenue for developing cost-effective and stable HTMs for PSCs and other optoelectronic devices.

The surface and boundary defects present in the perovskite film are reported to be nonradiative recombination and degradation centers, restricting further improvement of the power conversion efficiency (PCE) and long-term stability of perovskite solar cells. To address this problem, herein, we introduce a fluorine-substituted small molecular material 2FBTA-1 as a bifunctional buffer layer to efficiently passivate the surface defects of perovskite and tune the energy level alignment between the perovskite/2,2',7,7'-tetrakis(N,N-di-(p-methoxyphenyl)amino)-9,9'-spirobifluorene (Spiro-OMeTAD) interface. X-ray photoelectron spectroscopy shows that with the insertion of 2FBTA-1 between perovskite and Spiro-OMeTAD, the metallic Pb0 defects and uncoordinated Pb2+ defects are well restricted. Consequently, the average PCE is distinctly improved from 18.4 ± 0.51 to 20.3 ± 0.40%. Moreover, the long-term stability of unencapsulated devices with 2FBTA-1 treatment under ambient conditions (relative humidity 40-60%) is effectively enhanced, retaining 87% of the initial efficiency after storage for 500 h.

Journal of the American Chemical Society 142(41), 17681 - 17692 (2020). doi:10.1021/jacs.0c08352, Conjugated polymers are regarded as promising candidates for dopant-free hole-transport materials (HTMs) in efficient and stable perovskite solar cells (PSCs). Thus far, the vast majority of polymeric HTMs feature structurally complicated benzo[1,2-b:4,5-b’]dithiophene (BDT) analogs and electron-withdrawing heterocycles, forming a strong donor–acceptor (D–A) structure. Herein, a new class of phenanthrocarbazole (PC)-based polymeric HTMs (PC1, PC2, and PC3) has been synthesized by inserting a PC unit into a polymeric thiophene or selenophene chain with the aim of enhancing the $π–π$ stacking of adjacent polymer chains and also to efficiently interact with the perovskite surface through the broad and planar conjugated backbone of the PC. Suitable energy levels, excellent thermostability, and humidity resistivity together with remarkable photoelectric properties are obtained via meticulously tuning the conformation and elemental composition of the polymers. As a result, PSCs containing PC3 as dopant-free HTM show a stabilized power conversion efficiency (PCE) of 20.8% and significantly enhanced longevity, rendering one of the best types of PSCs based on dopant-free HTMs. Subsequent experimental and theoretical studies reveal that the planar conformation of the polymers contributes to an ordered and face-on stacking of the polymer chains. Furthermore, introduction of the “Lewis soft” selenium atom can passivate surface trap sites of perovskite films by Pb–Se interaction and facilitate the interfacial charge separation significantly. This work reveals the guiding principles for rational design of dopant-free polymeric HTMs and also inspires rational exploration of small molecular HTMs., Published by American Chemical Society, Washington, DC

Perovskite photovoltaics have recently attracted extensive attention due to their unprecedented high power conversion efficiencies (PCEs) in combination with primitive manufacturing conditions. How ...

The identification of an efficient and stable redox mediator is of paramount importance for commercialization of dye-sensitized solar cells (DSCs). Herein, we report a new class of copper complexes containing diamine-dipyridine tetradentate ligands (L1 = N, N'-dibenzyl- N, N'-bis(pyridin-2-ylmethyl)ethylenediamine; L2 = N, N'-dibenzyl- N, N'-bis(6-methylpyridin-2-ylmethyl)ethylenediamine) as redox mediators in DSCs. Devices constructed with [Cu(L2)]2+/+ redox couple afford an impressive power conversion efficiency (PCE) of 9.2% measured under simulated one sun irradiation (100 mW cm-2, AM 1.5G), which is among the top efficiencies reported thus far for DSCs with copper complex-based redox mediators. Remarkably, the excellent air, photo, and electrochemical stability of the [Cu(L2)]2+/+ complexes renders an outstanding long-term stability of the whole DSC device, maintaining ∼90% of the initial efficiency over 500 h under continuous full sun irradiation. This work unfolds a new platform for developing highly efficient and stable redox mediators for large-scale application of DSCs.

P-type doping is a rational strategy for the enhancement of hole transporting properties of the organic semiconductors as well as the device performance of organic photo-electric devices. We originally introduce a stable and solution processed p-type dopant based on N-oxoammonium salts termed 2,2,6,6-tetramethyl-1-oxopiperidinebromide salt (TEMPO-Br) for 2,2′,7,7′-tetrakis(N, N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene (Spiro-OMeTAD) based solid state dye sensitized solar cells (ssDSC). By introducing TEMPO-Br doped Spiro-OMeTAD and a commercialized D-π-A sensitizer into ssDSCs, a promising device performance of 6.83% is achieved under simulated AM 1.5G solar irradiation (100 mW cm−2), which is significantly better than the control devices (∼1.7 times). The doping effect of TEMPO-Br on the photophysical and electrochemical properties of Spiro-OMeTAD, solid state device performance, cationic dye regeneration kinetics and preliminary long-term stability have been systematically investigated. This work indicates a potential application of N-oxoammonium salts as chemical P-type dopants for triphenylamine based hole transporting materials in solid state photo-electric devices.

Disseminated nocardiosis is a rare disease mostly occurring in immunocompromised patients. We report a case of disseminated nocardiosis in a diabetic patient with both pulmonary and cutaneous involvement. Nocardia elegans was isolated and identified using the 16s ribosomal RNA gene sequence data. Clinical improvement was observed within 3 months after initiation of antimicrobial treatment with oral doxycycline, trimethoprim-sulfamethoxazole and intravenous penicillin, but the patient died 5 months later after arbitrary discontinuation of the treatment. This is the first case report of disseminated nocardiosis caused by Nocardia elegans in China.

In recent years the photovoltaic community has witnessed the unprecedented development of perovskite solar cells (PSCs) as they have taken the lead in emergent photovoltaic technologies. The power conversion efficiency of this new class of solar cells has been increased to a point where they are beginning to compete with more established technologies. Although PSCs have evolved a variety of structures, the use of hole-transporting materials (HTMs) remains indispensable. Here, an overview of the various types of available HTMs is presented. This includes organic and inorganic HTMs and is presented alongside recent progress in associated aspects of PSCs, including device architectures and fabrication techniques to produce high-quality perovskite films. The structure, electrochemistry, and physical properties of a variety of HTMs are discussed, highlighting considerations for those designing new HTMs. Finally, an outlook is presented to provide more concrete direction for the development and optimization of HTMs for high-efficiency PSCs.

X1 (MeO-TPD) is an inexpensive and easily synthesized pi-conjugated molecule that has been used as a hole-transport material (HTM) in solid-state dye-sensitized solar cells (ssDSSCs), achieving rel ...

The low-cost and stable inorganic p-type semiconductor copper(I) iodide (CuI) is a promising hole-transporting layer (HTL) material for inverted planar perovskite solar cells (PSCs). However, the power conversion efficiencies (PCEs) of inverted planar PSCs based on CuI HTLs reported so far are not satisfactory and far behind those of their organic counterparts. Herein, we demonstrate a simple but effective approach to improve the performance of inverted planar PSCs based on the CuI HTL through the incorporation of copper thiocyanate (CuSCN) into the CuI HTL. As compared to pristine CuI, the introduction of CuSCN significantly improves the quality of the film, resulting in a smooth and uniform film while maintaining relatively high electrical conductivity. As a consequence, the champion device based on the composite CuI/CuSCN HTL affords an impressive PCE of 18.76% under full sun illumination (100 mW cm−2, AM 1.5G), which is substantially higher than the corresponding values of the respective devices containing pristine CuI (14.53%) and CuSCN (16.66%). This value is one of the highest efficiencies reported thus far for CuI- and CuSCN-based HTLs in PSCs. This work demonstrates the great potential of low-temperature solution-processed CuI/CuSCN composites as hole-selective layers for low-cost and efficient PSCs as well as other optoelectronic devices.

Perovskite films are apt to format defects on surface and in grain boundaries, which results in inferior photovoltaic performance. Moreover, perovskite materials are sensitive to Ultraviolet (UV) light and are easily damaged under UV light illumination, accelerating the degradation of Perovskite solar cells (PSCs). Therefore, it is significant to design and develop effective defect passivation and UV inhibitors for efficient and stable PSCs. Herein, a small molecular material 2,5-bis(perfluorophenyl)thiazolo[5,4-d]thiazole (PFP2TTz) was designed and introduced into the perovskite precursor solution. The research manifested that PFP2TTz is a bifunctional additive, acting as both defect passivation and Fluorescence resonance energy transfer (FRET) agents. Through FRET action, the spectrum response in the short wavelength region and the device stability under UV light illumination were remarkably enhanced. Moreover, the PFP2TTz-treatment can significantly decrease the trap state density of perovskite film. Correspondingly, the PFP2TTz-treated PSC device exhibited an impressive Power conversion efficiency (PCE) of 21.38%, which is much higher than the control device (19.27%). Meanwhile, the unencapsulated PFP2TTz-treated PSC device exhibits long-term stability, maintaining their initial PCE of 90.4% up to 30 days under relative humidity of 45–55%.

In order to further boost the photovoltaic performance of all-inorganic perovskite solar cells (PSCs), great efforts are needed to synergistically develop high-quality perovskite film and highly efficient charge transport materials. In view of the fact that large number of researchers have devoted to optimizing the crystal composition and crystallization kinetics, we chose to carry out the study from the perspective of hole transport layer. Herein, we designed and synthesized two low-cost fluorene terminal-modified hole transport materials (HTMs), termed YT-MPF and YT-FF. Moreover, through the modification of peripheral groups, the electrostatic surface potentials of HTMs are well regulated. The HTM YT-MPF with one peripheral fluorene arm on each side exhibits a more polarized structure, which facilitates the intermolecular interaction and hole hopping transport. Applied YT-MPF in CsPbI2Br based all-inorganic PSC, an impressive power conversion efficiency (PCE) of 16.0% with fairly high open-circuit voltage (Voc) of 1.29 V is obtained, outperforming that of the control devices based on traditional HTM PTAA (12.7%) and Spiro-OMeTAD (14.7%). Our research supplies an effective way to push up the performance of CsPbI2Br PSC.

As a champion hole-transporting material (HTM), 2,27,7-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (Spiro-OMeTAD) has been widely used in solid-state dye-sensitized solar cells (ssDS ...

The development of an efficient, stable, and low-cost hole-transporting material (HTM) is of great significance for perovskite solar cells (PSCs) from future commercialization point of view. Herein, we specifically synthesize a dicationic salt of X60 termed X60(TFSI)2, and adopt it as an effective and stable “doping” agent to replace the previously used lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) for the low-cost organic HTM X60 in PSCs. The incorporation of this dicationic salt significantly increases the hole conductivity of X60 by two orders of magnitude from 10−6 to 10−4 S cm−1. The dramatic enhancement of the conductivity leads to an impressive power conversion efficiency (PCE) of 19.0% measured at 1 sun illumination (100 mW cm−2, AM 1.5 G), which is comparable to that of the device doped with LiTFSI (19.3%) under an identical condition. More strikingly, by replacing LiTFSI, the PSC devices incorporating X60(TFSI)2 also show an excellent long-term durability under ambient atmosphere for 30 days, mainly due to the hydrophobic nature of the X60(TFSI)2 doped HTM layer, which can effectively prevent the moisture destroying the perovskite layer. The present work paves the way for the development of highly efficient, stable, and low-cost HTM for potential commercialization of PSCs.

Colloidal quantum dot (CQD) solar cells with a ZnO/PbS-TBAI/PbS-EDT/carbon structure were prepared using a solution processing technique. A commercially available carbon paste that was processed at low-temperatures was used as a counter electrode in place of expensive noble metals, such as Au or Ag, which are used in traditional PbS CQD solar cells. These CQD solar cells exhibited remarkable photovoltaic performance with a short circuit density (Jsc) of 25.6 mA/cm2, an open circuit voltage (Voc) of 0.45 V, a fill factor (FF) of 51.8% and a power conversion efficiency (PCE) as high as 5.9%. A reference device with an Au counter electrode had a PCE of 6.0%. The PCE of the carbon-containing CQD solar cell remained stable for 180 days when tested in ambient atmosphere, while the PCE of the Au-containing CQD solar cell lost 48.3% of its original value. Electrochemical impedance spectroscopy (EIS) demonstrated that holes within the PbS CQD were effectively transported to the carbon counter electrode.

Dopant-free hole-transport material (HTM) is essential to the long-term stability of the perovskite solar cells (PSCs). This study has introduced a novel carbazole-based dopant-free HTM via the simple ring-closing reaction without using the expensive catalyst. It has found that the merger of a higher rigid conjugated ring into the molecular geometry of HTM is an effective way to improve its charge extraction ability, hole mobility and phase thermal stability. Consequently, a power conversion efficiency (PCE) of 16.4% as well as a much-improved long-term stability have been achieved based on the as-prepared C302 dopant-free HTM.

Through molecular engineering, phenothiazine-based monomer hole transport material (HTM) PTZT and dimer HTM D-PTZT were designed and synthesized. The photoelectrochemical properties are significantly influence by the adjustment of the molecular structure. Applied in perovskite solar cells (PSCs), monomer HTM PTZT-based device achieves the highest efficiency of 18.74% while only 15.45% for dimer HTM D-PTZT-based device under 100 mW cm−2 AM 1.5G solar illumination.

The inorganic p-type semiconductor CuI possesses several unique characteristics such as high transparency, low-production cost, high hole mobility, and good chemical stability and is a promising ho ...

In high-performance perovskite solar cells (PSCs), hole-transporting materials (HTMs) play an important role in extracting and transporting the photo-generated holes from the perovskite absorber to the cathode, thus reducing unwanted recombination losses and enhancing the photovoltaic performance. Herein, solution-processable tetra-4-(bis(4-tert-butylphenyl)amino)phenoxy-substituted copper phthalocyanine (CuPc-OTPAtBu) was synthesized and explored as a HTM in PSCs. The optical, electrochemical, and thermal properties were fully characterized for this organic metal complex. The photovoltaic performance of PSCs employing this CuPc derivative as a HTM was further investigated, in combination with a mixed-ion perovskite as a light absorber and a low-cost vacuum-free carbon as cathode. The optimized devices [doped with 6 % (w/w) tetrafluoro-tetracyano-quinodimethane (F4TCNQ)] showed a decent power conversion efficiency of 15.0 %, with an open-circuit voltage of 1.01 V, a short-circuit current density of 21.9 mA cm−2, and a fill factor of 0.68. Notably, the PSC devices studied also exhibited excellent long-term durability under ambient condition for 720 h, mainly owing to the introduction of the hydrophobic HTM interlayer, which prevents moisture penetration into the perovskite film. The present work emphasizes that solution-processable CuPc holds a great promise as a class of alternative HTMs that can be further explored for efficient and stable PSCs in the future.