A mixed metal oxide-coated Ti felt was constructed for use as a porous transport layer (PTL) in a proton exchange membrane (PEM) water electrolyzer. The PTL was fabricated by coating Ti felt with ...0.43 mgTaOx cm−2 and 1 mgIr + Ru cm−2 IrO2–RuO2-TaOx using a thermal decomposition method. The coated Ti felts exhibited high conductivity, mass transport performance, stability and oxygen evolution reaction (OER) catalytic activities. The stability of IrO2–RuO2-TaOx coating obviously improved than traditional electroplated Pt coating. Using the PTL, a single cell performance of 1.836 V @ 2000 mA cm−2 was achieved at 80 °C under ambient pressure with 1 mg cm−2 of precious metal in anode CL. However, the precious metal loading is about 2 mg cm−2 in common PEM electrolyzer anode catalyst layer (CL). The IrO2–RuO2-TaOx-coated Ti felt proved to be a promising low-cost PTL for PEM water electrolysis with high performance.
•The TaOx improved the stability of IrO2–RuO2-TaOx coating as PTL.•The IrO2–RuO2-TaOx coated Ti felt as PTL showed great performance in PEM electrolyzer.•With IrO2–RuO2-TaOx coating, a single cell performance of 1.836 V @ 2 A cm−2 was achieved with 1 mg cm−2 Ir in anode CL.
The interface V OC loss between the active layer and the hole transport layer (HTL) of lead sulfide colloidal quantum dot (PbS-CQD) solar cells is a significant factor influencing the efficiency ...improvement of PbS colloidal quantum dot solar cells (PbS-CQDSCs). Currently, the most advanced solar cells adopt organic P-type HTLs (PbS-EDT) via solid-state ligand exchange with 1,2-ethanedithiol (EDT) on the CQD top active layer. However, EDT is unable to altogether remove the initial ligand oleic acid from the quantum dot surface, and its high reactivity leads to cracks in the HTL film caused by volume contractions, which inevitably results in significant V OC loss. These flaws prompted this research to develop a method involving hybrid organic ligand exchange using 3-mercaptopropionic acid (MPA) and 1,2-EDT (PbS-Hybrid) to overcome these drawbacks of V OC loss. The results indicated that the new exchange strategy improved the quality of the HTL film and benefited from the enhanced passivation of the quantum dot surface and better alignment of energy levels, and the average V OC of PbS-Hybrid devices is increased by approximately 25 mV compared to control devices. With the enhanced V OC, the average power conversion efficiency (PCE) of the devices is improved by 10%, with the highest PCE reaching 13.24%.
Defect accumulation and nonradiative recombination at the interface of the electron-transport layer (ETL) and the photosensitive layer are inevitable obstacles to efficient and stable perovskite ...solar cells (PSCs). Herein, we reported a dual-effect interface modification strategy that employs potassium tetrafluoroborate (KBF4) molecules for the simultaneous passivation of the SnO2/perovskite interface and perovskite grain boundaries. The introduced highly electronegative BF4 – enriched at the SnO2 surface and the chemical bond interaction between them can effectively reduce the hydroxyl (−OH) group defects on the surface of SnO2, improve electron mobility, and reduce nonradiative recombination. Meanwhile, partial K+ diffuses into the grain boundaries, causing the halogen ions to be uniformly distributed in the perovskite film and resulting in better crystallinity. Therefore, the performance of the experimental device was improved from 20.34 to 22.90% compared with the reference device, with a high electrical performance (J SC = 25.1 mA cm–2, V OC = 1.137 V). In particular, the unencapsulated target PSCs retained 85% of their original PCE after aging for 1000 h under ambient conditions (70 ± 10% RH) in the dark.
We show enhanced efficiency and stability of a high performance organic solar cell (OPV) when the work‐function of the hole collecting indium‐tin oxide (ITO) contact, modified with a ...solution‐processed nickel oxide (NiOx) hole‐transport layer (HTL), is matched to the ionization potential of the donor material in a bulk‐heterojunction solar cell. Addition of the NiOx HTL to the hole collecting contact results in a power conversion efficiency (PCE) of 6.7%, which is a 17.3% net increase in performance over the 5.7% PCE achieved with a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL on ITO. The impact of these NiOx films is evaluated through optical and electronic measurements as well as device modeling. The valence and conduction band energies for the NiOx HTL are characterized in detail through photoelectron spectroscopy studies while spectroscopic ellipsometry is used to characterize the optical properties. Oxygen plasma treatment of the NiOx HTL is shown to provide superior contact properties by increasing the ITO/NiOx contact work‐function by 500 meV. Enhancement of device performance is attributed to reduction of the band edge energy offset at the ITO/NiOx interface with the poly(N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothidiazole) (PCDTBT):6,6‐phenyl‐C61 butyric acid methyl ester PCBM and 6,6‐phenyl‐C71 butyric acid methyl ester (PC70BM) active layer. A high work‐function hole collecting contact is therefore the appropriate choice for high ionization potential donor materials in order to maximize OPV performance.
Enhanced efficiency and stability of a high performance organic solar cell is demonstrated when the hole collecting indium‐tin oxide contact is modified with solution‐processed nickel oxide and the high work‐function contact is matched with the donor ionization potential. We use photoemission spectroscopy to characterize the band edge positions in the contact layer, a multilayer matrix optical model and a diode model to explain the improvements in contact quality in comparison to the hole‐transport layer, polyethylene dioxythiophene:polystyrene sulfonate.
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•The introduction of potassium bitartrate (KBT) into the TiO2 film improves TiO2 surface smoothness and charge transport, reducing recombination centers in PSCs.•KBT in TiO2 ETLs ...enhances PSC morphology, reduces interface defects, and improves energy alignment, leading to higher efficiency and stability.•PSCs with KBT show a significant efficiency increase to 23.35 % and maintain over 80 % efficiency after 800 h.
The performance of perovskite solar cells (PSCs) has rapidly improved, largely due to advancements in mitigating inherent defects and enhancing interface carrier transport properties. Herein, we provide a facile method to improve the morphology of TiO2 ETLs, suppress defects at interface, and tailor energy level alignment to enhance carrier separation and extraction efficiency by introducing potassium bitartrate (KBT) into the TiO2 electron transport layers (ETLs), achieving high-efficiency and stable PSCs. KBT molecules can enhance the surface smoothness of TiO2 ETLs, resulting in denser and more uniform perovskite films. In addition, the carboxyl groups, hydroxyl groups, and potassium cations containing in KBT improve charge transport efficiency at TiO2/perovskite interface by reducing non-radiative recombination centers in TiO2 and perovskite bottom as well as improving energy level matching. As a result, the target PSC exhibits an obvious improvement in performance with a champion efficiency of 23.35 %, which is greatly improved relative to the control (21.66 %). The long-term operational stability is also remarkably enhanced, after 800 h MPPT, PSCs with KBT remain over 80 % of its initial efficiency. PSCs with KBT-doped ETLs exhibit increased efficiency and stability, highlighting potential of KBT as an interface engineering tool for enhancing PSCs performance.
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•TSAPS effectively inhibited the oxygen vacancy on SnO2 surface, which leads to oxygen vacancy decreased from 68.40% to 45.26%.•The unencapsulated SnO2/TSAPS-based flexible device can ...maintain 84% of its initial efficiency after 3000 bending cycles, while the control one sharply decrease to 9%.•Surface and bulk defects in perovskite have been greatly restrained after TSAPS modification, resulting in enhanced PCE from 15.22% to 18.63% for flexible PSCs.
Flexible perovskite solar cells (F-PSCs) are currently a research hotspot due to their lightweight, solution processability, and low cost. However, oxygen vacancies in SnO2 would deteriorate the crystallization of perovskite, especially in F-PSCs due to the low temperature of SnO2 preparation with flexible substrates, thus inducing poor performance and decreased bending resistance. Here, trichlorobenzene sulfonic acid potassium salt (TSAPS) is used as an effective oxygen vacancy restrain additive on the SnO2 surface for F-PSCs. The oxygen vacancies are reduced from 68.40% to 45.26% after TSAPS modification. Meanwhile, the interfacial defects are suppressed by the synergistic passivation of individual ions in TSAPS, thus the carrier extraction and transportation are effectively improved. As a result, the PCE of the F-PSCs greatly increased from 15.22% to 18.63%. In addition, the unencapsulated SnO2/TSAPS-based flexible device can maintain 84% of its initial efficiency after 3000 bending cycles, exhibiting superior mechanical stability, while the control one decreased to only 9%. This work demonstrates a dependable method for improving the quality of the interface between the ETL and perovskite layer, resulting in enhanced bending resistance and performance for flexible PSCs.
Organic-inorganic lead halide perovskites are promising materials for realization of low-cost and high-efficiency solar cells. Because of the toxicity of lead, Sn-based perovskite materials have been ...developed as alternatives to enable fabrication of Pb-free perovskite solar cells. However, the solar cell performance of Sn-based perovskite solar cells (Sn-PSCs) remains poor because of their large open-circuit voltage (
) loss. Sn-based perovskite materials have lower electron affinities than Pb-based perovskite materials, which result in larger conduction band offset (CBO) values at the interface between the Sn-based perovskite and a conventional electron transport layer (ETL) material such as TiO
. Herein, the relationship between the
and the CBO in these devices was studied to improve the solar cell performances of Sn-PSCs. It was found that the band offset at the ETL/perovskite layer interface affects the
of the Sn-PSCs significantly but does not affect that of the Pb-PSCs because the Sn-based perovskite material is a
-type semiconductor, unlike the Pb-based perovskite. It was also found that Nb
O
has the CBO that is closest to zero for Sn-based perovskite materials, and the
values of Sn-PSCs that use Nb
O
as their ETL are higher than those of Sn-PSCs using TiO
or SnO
ETLs. This study indicates that control of the energy alignment at the ETL/perovskite layer interface is an important factor in improving the
values of Sn-PSCs.
Perovskite solar cells (PSCs) have shown great potential for reducing costs and improving power conversion efficiency (PCE). One effective method to achieve the latter is to use an all-inorganic ...charge transport layer (ICTL). However, traditional methods for crystallizing inorganic layers often result in the formation of a powder instead of a continuous film. To address this issue, we designed a dual-layer inorganic electron transport layer (IETL). This dual-layer structure consists of a layer of SnO2 nanocrystals (SnO2 NCs) deposited via a solution process and a dense SnO2 layer deposited through atomic layer deposition (ALD SnO2) to fill the cracks and gaps between the SnO2 NCs. PSCs having these dual-layer SnO2 ETLs achieved a high efficiency of 23.0%. This efficiency surpasses the recorded performance of ICTLs deposited on the perovskite. Furthermore, the PCE is comparable to that achieved with a C60 ETL. Moreover, the high-density structure of the ALD SnO2 layer inhibits the vertical migration of ions, resulting in improved thermal stability. After continuous heating at 85 °C in 10% humidity for 1000 h, the PCE of the dual-layer SnO2 structure decreased by 18%, whereas that of the C60/BCP structure decreased by 36%. The integration of dual-layer SnO2 into PSCs represents a significant advancement in achieving high-performance, commercially viable inverted monolithic PSCs or tandem solar cells.
The electron transport layer (ETL) plays an important role in the performance and stability enhancement of perovskite solar cells (PSCs). Zinc oxide is considered a cost-effective and low-temperature ...processed ETL for PSCs, which offers decent mobility. However, the interface reaction occurs via a reaction of zinc oxide with the organic-inorganic metal hybrid halide perovskite absorber, which results in the degradation of the PSCs. To overcome this issue, metal doping was carried out. However, metal doping causes a reduction in the transmittance of the zinc oxide ETL layer because of high absorption. Thus, the overall performance of the PSCs was reduced due to the lessening of the photogenerated current. In this regard metal co-doping (Mn and Co) was done to improve the electrical as well as electronic properties. Furthermore, the influence of Mn doping on the structural, optical, and photoluminescence properties of MnxCo0.015Zn1-xO (x = 0, 0.002, 0.008, and 0.012) hexagonal nanosheets was investigated. X-ray diffraction results revealed that the inter-planar spacing, cell parameters, unit cell volume, lattice strain, and dislocation density were maximum for the Mn content of 0.2%. The acquired values of the optical band gap (Eg) are 3.39, 3.52, 3.58, and 3.18 eV for x = 0, 0.2%, 0.8%, and 1.2%, respectively. The corresponding absorption coefficient is reduced with increasing Mn content. The obtained refractive indices are 1.437, 1.402, 1.428, and 1.426 for x = 0, 0.2, 0.8, and 1.2%, respectively. The above results confirm that the MnxCo0.015Zn1-xO with x = 0.8% provides the lowest absorption and the highest value of bandgap. Thus, it can be the most suitable ETL for high-performance PSCs. The simulation results reveal that via applying MCZO ETL, the efficiency can be achieved over 23%.
•New ZnO-based compounds (MnxCo0.015Zn1-xO) were synthesized via the Co-doping of Mn and Co into ZnO.•Influence of Mn doping in Co–ZnO (CZO) was investigated on some of the properties of ZnO.•Highest values of cell parameters were obtained for Mn doping of 0.2%.•The value of the absorption coefficient was reduced with increasing Mn content.•All the samples offer a refractive index value of less than 1.5.
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