SnO2 has attracted considerable attention in perovskite solar cells (PSCs) due to its excellent optical and electrical properties. However, a poor surface morphology, specifically with the presence ...of pinholes after the annealing process, limits its application in PSCs. To overcome the drawback of tin oxide, lanthanum (La) is herein first to be doped into the SnO2 layer, which is able to alleviate the SnO2 crystal aggregation and produce full-coverage and a uniform film. In addition, La:SnO2 can effectively reduce the band offset of the SnO2 layer, which results in the high Voc of 1.11 V. Systematic analyses revealed that the La:SnO2 layer enhances the electron extraction and suppresses charge recombination, leading to the power conversion efficiency (PCE) enhancement from 14.24% to 17.08%.
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•La doped SnO2 was ETL for planar PSCs with PCE of 17.08%.•La doping is a feasible strategy for improving the PCE.
The rational design and modification of the buried interface are essential and challenging for high-performance perovskite solar cells (PSCs). TiO2 is a simple and readily available electron ...transport layer material, but its surface defects and poor interfacial contact with perovskite layers hinder its widespread application. Here, we propose an effective TiO2/perovskite interface modification strategy by introducing simple guanidine carbonate (GuaCO3) onto the surface of TiO2. Guanidine carbonate can improve the interfacial contact between TiO2 and perovskite, reduce non-radiative recombination, and enhance carrier extraction. Moreover, the PbI2 film grown on the TiO2/GuaCO3 substrate tended to become porous during the preparation of perovskite films by the traditional two-step method, which facilitated the complete reaction of organic ammonium salts with PbI2 and promoted the growth of high-quality perovskite films. The experimental results indicate that GuaCO3 can passivate the interfacial defects of TiO2/perovskite, as well as reduce the accumulation of interfacial charges. The device modified with GuaCO3 achieved a power conversion efficiency (PCE) of 23.39 %, which is significantly higher than that of the control device (21.73 %). After storage in an ambient environment at room temperature for 600 h, the unencapsulated device modified with GuaCO3 retained 78 % of its initial efficiency, while the control device retained only 57 % of its initial efficiency. These results indicate that interfacial modification with GuaCO3 is an effective strategy for improving the performance of PSCs.
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•GuaCO3 was introduced into the TiO2/perovskite interface as a modified layer.•GuaCO3 can passivate the surface defects of TiO2 ETLs.•GuaCO3 promotes the formation of loose and porous morphology in PbI2 films.•The PCE and stability of the device modified with GuaCO3 were improved.
The highest power conversion efficiency of perovskite solar cells is beyond 22%. Charge transport layers are found to be critical for device performance and stability. A traditional electron ...transport layer (ETL), such as TiO2, is not very efficient for charge extraction at the interface, especially in planar structure. In addition, the devices using TiO2 suffer from serious degradation under ultraviolet illumination. SnO2 owns a better band alignment with the perovskite absorption layer and high electron mobility, which is helpful for electron extraction. In this Review, recent progresses in efficient and stable perovskite solar cells using SnO2 as ETL are summarized.
SnO2 is a suitable electron transport layer (ETL) in perovskite solar cells considering its high mobility, deep conduction band and good chemical stability. Perovskite solar cells based on SnO2 show power conversion efficiency of 21.6%, and over 1000 h of photo‐soaking stability is reported. Here, recent progress in efficient and stable perovskite solar cells using SnO2 as ETL are summarized.
Antimony selenide (Sb2Se3) emerges as a promising semiconductor for solar energy conversion, attributed to its high light absorption and excellent photoelectric properties, coupled with notable ...stability and consistent stoichiometry. Yet, its application in thin-film solar cells is limited by non-radiative recombination losses at suboptimal heterojunction interfaces. Addressing this, we propose a strategy employing a C60 electron transport layer (ETL), thermally evaporated between the Sb2Se3 absorber and SnOx buffer layer. This approach not only increases the carrier density in SnOx but also passivates harmful defects like VO and OH−, thus reducing interfacial recombination. Incorporating C60 ETL improves the fill factor (FF) and open-circuit voltage (VOC) of the Sb2Se3 device, achieving a maximum power conversion efficiency (PCE) of 6.65 %. This finding highlights the significance of ETL-dependent interfacial engineering in enhancing Sb2Se3 solar cell performance, offering a novel and accessible solution to the primary challenge in developing Cd-free Sb2Se3 solar cells.
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•The MoS2/BiVO4/pre-FTO-MoS2/Ni foam PFC was constructed for the first time.•The TiO2 electron transport layer significantly facilited the charge transfer.•The 2D MoS2 shortened ...photogenerated electron migration pathway.•MoS2/Ni foam served as the photocathode.•The degradation efficiency was strongly affected by h+ and O2–.
The poor contact between the photocatalyst and the FTO substrate are the main factors lead to the low performance of photocatalytic fuel cell (PFC). Herein, a FTO pre-treated with a TiO2 electron transport layer was used as a substrate for the synthesis of the MoS2/BiVO4/pre-FTO photoanode. The proposed MBV-4/pre-FTO photoanode with its enhances the visible light absorption and effectively delays the recombination of the photoexcited charge. The MBV-4/pre-FTO composite photoanode (6.02 mA/cm2) exhibited a photocurrent density that was 2.2 times higher than that of the BiVO4 photoanode (2.78 mA/cm2). This is attributed to the short charge migration length of the thin MoS2 layer, the fast photoexcited electron transport effect of the TiO2 seed layer, and the heterojunction structure of the proposed photoanode. The DFT calculation result indicated that the TiO2 electron transport layer showed an outstanding photoelectron attractive and transporting effect. The MoS2/Ni foam was employed as the photocathode to establish a mismatched Fermi level for driving PFC. The short-circuit current, open-circuit voltage, and maximum power density of the PFC were 0.578 mA/cm2, 0.632 V, and 0.125 mW/cm2, respectively. The main photodegradation active species are the superoxide anion (∙O2–) and the photoexcited hole (h+), and the degradation efficiency is 61.97 %.
•The photovoltaic characteristics of ZnO layer effects on the PSCs is studied.•The morphology of layer ZnO layer thickness was investigated by SEM and AFM.•ZnO layer thickness increased, the (ECE) is ...also increased to 15.22%.•The high ECE was due to the enhanced electrical conductivity ZnO layer.•The surface valley spacing in the ZnO layer may affect the grain size and thickness.
The energy loss in perovskite solar cells (PSCs) is a key factor that limits the potential scope of photovoltaic performance. Herein, we introduce a double electron transport layer (DETL) that consists of SnO2/ZnO and use it to prepare methylammonium lead triiodide (MAPbI3)-based planar heterojunction PSCs for mitigating the energy loss. We investigated the photovoltaic properties of DETL PSCs concerning the varying thickness of the ZnO layer. The thickness of DETL in each device was measured using an electron probe microanalyzer. UV–vis-NIR spectroscopic as well as different microscopic techniques including SEM and AFM were employed for an in-depth investigation of the prepared devices. The best PSC device in our study showed a comparatively improved energy conversion efficiency (ECE) of 15.22% with an optimized thickness of ZnO up to 210 nm.
ZnO surface modified by NAOs to obtain high-efficiency and stable IOSCs by decreasing the WF of ZnO and removing the charge recombination center (–OH) at ZnO surface.
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•ZnO film is ...firstly modified with three environment-friendly natural antioxidants (NAOs).•The modification of NAOs lowers the work function of ZnO surface.•NAOs also effectively passivates the defects of ZnO surface.•Inverted organic solar cells (IOSCs) with new ETLs are firstly fabricated.•The performance of IOSC with ZnO modified by NAOs as ETLs is obviously increased.
Zinc oxide (ZnO) has proved to be an effective electron transport layer (ETL) in organic solar cells (OSCs). However, a variety of defects on ZnO surface and improperly matched work function (WF) greatly restrict the ability of charge transportationinthe OSCs. Surface modification is an effective strategy for solving these problems. In this work, the ZnO film is modified with three environment-friendly natural antioxidants (NAOs): caffeic acid (CA), ferulic acid (FA) and 3, 4-dimethoxy cinnamic acid (DMCA), respectively. The results show that the modification of NAOs not only effectively passivates the defects of ZnO surface, but also lowers the WF of ZnO by forming interface dipoles and upward shift of Fermi level of ZnO. Moreover, the inverted organic solar cells (IOSCs) with ZnO modified by NAOs as ETLs are firstly fabricated. As the result, the IOSC based on PBDB-T: ITIC obtains the increased PCE of 11.75% (ZnO/CA), 11.25% (ZnO/FA) and 10.90% (ZnO/DMCA), which is higher than those of the reference 10.15% (ZnO). Meanwhile, the PCE of IOSC based on PM6:L8-BO with ZnO/CA ETL is also obviously increased from 16.41% to 18.22%. The ambient stability of the IOSCs new ETLs is also significantly improved due to the increased hydrophobicity of ETL and the enhanced crystallinity of active layer. The novel ETLs provide a facile, eco-friendly, low-cost method to realize the efficient and stable photovoltaic devices.
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•Stabilize SnO2 colloids with EDTA-2M (M represents K, Rb or Cs).•Improve the electrical and surface properties of the SnO2 films with EDTA-2M.•Promote the quality of the perovskite ...films with EDTA-2M.•The 1.57 eV bandgap PSCs realized a champion efficiency of 23.30% (VOC = 1.171V).•The 1.69eV bandgap PSCs reached an efficiency of 19.76% (VOC = 1.266V).
The electron transport layer (ETL) is of great importance for preparing high-efficiency perovskite solar cells (PSCs). Here we introduced EDTA-2 M (M represents K, Rb or Cs) molecules to stabilize SnO2 colloids, and improve the electrical and surface properties of the SnO2 films. With the help of EDTA-2 M, the electron mobility of SnO2-based perovskite films is increased from 3.6 × 10-4 to 1.27 × 10-3 cm2V-1s−1. In addition, EDTA-2 M molecules can effectively passivate the interface defects of SnO2 and promote the quality of the perovskite films. All the improvements suppress the carrier recombination, leading to a smaller open circuit voltage (VOC) loss. Finally, the 1.57 eV bandgap PSCs based on EDTA-2 M modified SnO2 realized a champion efficiency of 23.30% (VOC = 1.171 V) with a negligible hysteresis, while the 1.69 eV bandgap perovskite device reached an efficiency of 19.76% (VOC = 1.266 V). The unencapsulated PSCs based on EDTA-2 M modified SnO2 only drop 5% of the initial efficiency after being exposed to the ambient atmosphere for 1200 h.
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•Tetramethylammonium chloride (TMACl) was used as a passivator for SnO2.•TMACl can effectively passivate the defects at the SnO2/perovskite interface.•TMACl can improve the film ...quality of perovskite through thermal diffusion.•The devices with TMACl exhibit better device performance than the pristine device.•TMACl modified device shows the best PCE of 23.08%, along with excellent stability.
Intrinsic defects in the electron transport layer (ETL) and perovskite (PVK) layer, as well as energy level mismatch between the PVK and ETL, severely limit the device performance of perovskite solar cells (PSCs). Here, we introduced a multifunctional molecule (tetramethylammonium chloride, TMACl) as a passivator in the SnO2 ETL. During the annealing treatment, the defects in SnO2 ETL are suppressed by passivating the oxygen vacancies on the surface of SnO2. Moreover, the presence of TMACl enables the defects inevitably generated during the annealing process of PVK to be effectively passivated by the migrating TMA+ cations and Cl− anions. The characterization results further confirm that the surface modification of TMACl is more favorable for the suppression of interfacial recombination and the passivation of bulk and grain boundary defects of PVK compared to the bulk doping method. It is noteworthy that, compared with the pristine device (21.02%), the devices based on TMACl-doped SnO2 and TMACl-modified SnO2 ETLs obtained superior champion efficiencies of 22.71% and 23.08%, respectively. More importantly, the unencapsulated PSCs based on TMACl-modified SnO2 maintained 88% of their original efficiency during 35 days of storage in a humidity-controlled chamber with a relative humidity of 20–30%, demonstrating the passivation of SnO2 ETL using TMACl salts is an effective and promising approach to achieving high photovoltaic performances of PSCs.
