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Developing a universal strategy of the p–n homojunction engineering that could significantly boost electron mobility of electron transport layer (ETL) by two orders of magnitude. Proposing a new mechanism based on p–n homojunction to explain inhibited carrier loss at buried interface. Setting a new performance benchmark as high as 25.50% for planar perovskite solar cells employing TiO2 as ETLs. © The Author(s) 2024.

The effective separation and efficient transportation of photogenerated carriers within a photoanode are critical factors for achieving exceptional photoelectrochemical (PEC) water splitting. In this study, TiO2-Ferrihydrite (Fh) -MXene nanowire arrays (NWAs) are fabricated by hydrothermal method followed by spin-coating. TiO2-Fh-MXene NWAs achieved a photocurrent density of 1.44 mA/cm2 at 1.23 V versus reversible hydrogen electrode (vs. RHE), surpassing TiO2-Fh by 2.05 times and TiO2 by 2.93 times, respectively. According to the electrochemical impedance spectroscopy, photoluminescence and Mott-Schottky measurements, the significant enhancement in the separation of photogenerated electron-hole pairs and efficient carrier transportation are ascribed to the integration of Fh and MXene, respectively. Additionally, the light absorption of TiO2 NWAs is improved with the incorporation of the Fh-MXene layer. This work provides valuable insights into the fabrication of photoanodes, especially using wide bandgap materials.

Two inorganic electron-selective layers (ESLs), Sn1-xGexOy (TGO) and Zn1-xGexOy (ZGO), were developed by using atomic layer deposition (ALD) with in situ quartz crystal monitoring. To ensure (Ag,Cu)(In,Ga)Se-2 (ACIGS) solar cell compatibility, a 120 degrees C ALD process was developed for GeOy using Ge(N(CH3)(2))(4) and H2O as precursors. In the ALD supercycle approach, the GeOy ALD cycle was interchanged with either ZnO or SnOy cycles to deposit TGO and ZGO with varying conduction band positions (Ec), respectively. The material properties were experimentally verified using X-ray photoelectron spectroscopy and optical absorption and by employing these films as ESLs in ACIGS solar cells. There, the open-circuit voltage initially increased as the Ge content of the TGO and ZGO films increased due to the ESL E-c simultaneously shifting up from the low position in ZnO or SnOy to match the ACIGS E-c. As the Ge content increased further, the fill factor (FF) of these devices decreased since the ESL E-c became positioned significantly above the ACIGS E-c, forming an energy barrier as seen from ACIGS. As a result, the efficiency of the ACIGS solar cell peaked for an intermediate Ge content for both TGO and ZGO. Using good TGO and ZGO compositions in ACIGS solar cells gave efficiencies of up to 14.8 and 17.0%, respectively, which were lower than the reference best cell efficiencies of up to 19.5% for CdS and 18.2% for Zn1-xSnxOy (ZTO). ZGO was, however, able to shift its Ec further up than ZTO, making it a potent ESL for high-band-gap absorbers. Based on the results, we listed a few key properties that are required for a good ACIGS solar cell ESL and gave a few suggestions on how they are linked to the previous success of ZTO.

Two inorganic electron-selective layers (ESLs), Sn1-xGexOy (TGO) and Zn1-xGexOy (ZGO), were developed by using atomic layer deposition (ALD) with in situ quartz crystal monitoring. To ensure (Ag,Cu)(In,Ga)Se-2 (ACIGS) solar cell compatibility, a 120 degrees C ALD process was developed for GeOy using Ge(N(CH3)(2))(4) and H2O as precursors. In the ALD supercycle approach, the GeOy ALD cycle was interchanged with either ZnO or SnOy cycles to deposit TGO and ZGO with varying conduction band positions (Ec), respectively. The material properties were experimentally verified using X-ray photoelectron spectroscopy and optical absorption and by employing these films as ESLs in ACIGS solar cells. There, the open-circuit voltage initially increased as the Ge content of the TGO and ZGO films increased due to the ESL E-c simultaneously shifting up from the low position in ZnO or SnOy to match the ACIGS E-c. As the Ge content increased further, the fill factor (FF) of these devices decreased since the ESL E-c became positioned significantly above the ACIGS E-c, forming an energy barrier as seen from ACIGS. As a result, the efficiency of the ACIGS solar cell peaked for an intermediate Ge content for both TGO and ZGO. Using good TGO and ZGO compositions in ACIGS solar cells gave efficiencies of up to 14.8 and 17.0%, respectively, which were lower than the reference best cell efficiencies of up to 19.5% for CdS and 18.2% for Zn1-xSnxOy (ZTO). ZGO was, however, able to shift its Ec further up than ZTO, making it a potent ESL for high-band-gap absorbers. Based on the results, we listed a few key properties that are required for a good ACIGS solar cell ESL and gave a few suggestions on how they are linked to the previous success of ZTO.

Two inorganic electron-selective layers (ESLs), Sn1-xGexOy (TGO) and Zn1-xGexOy (ZGO), were developed by using atomic layer deposition (ALD) with in situ quartz crystal monitoring. To ensure (Ag,Cu)(In,Ga)Se-2 (ACIGS) solar cell compatibility, a 120 degrees C ALD process was developed for GeOy using Ge(N(CH3)(2))(4) and H2O as precursors. In the ALD supercycle approach, the GeOy ALD cycle was interchanged with either ZnO or SnOy cycles to deposit TGO and ZGO with varying conduction band positions (Ec), respectively. The material properties were experimentally verified using X-ray photoelectron spectroscopy and optical absorption and by employing these films as ESLs in ACIGS solar cells. There, the open-circuit voltage initially increased as the Ge content of the TGO and ZGO films increased due to the ESL E-c simultaneously shifting up from the low position in ZnO or SnOy to match the ACIGS E-c. As the Ge content increased further, the fill factor (FF) of these devices decreased since the ESL E-c became positioned significantly above the ACIGS E-c, forming an energy barrier as seen from ACIGS. As a result, the efficiency of the ACIGS solar cell peaked for an intermediate Ge content for both TGO and ZGO. Using good TGO and ZGO compositions in ACIGS solar cells gave efficiencies of up to 14.8 and 17.0%, respectively, which were lower than the reference best cell efficiencies of up to 19.5% for CdS and 18.2% for Zn1-xSnxOy (ZTO). ZGO was, however, able to shift its Ec further up than ZTO, making it a potent ESL for high-band-gap absorbers. Based on the results, we listed a few key properties that are required for a good ACIGS solar cell ESL and gave a few suggestions on how they are linked to the previous success of ZTO.

Two inorganic electron-selective layers (ESLs), Sn1-xGexOy (TGO) and Zn1-xGexOy (ZGO), were developed by using atomic layer deposition (ALD) with in situ quartz crystal monitoring. To ensure (Ag,Cu)(In,Ga)Se-2 (ACIGS) solar cell compatibility, a 120 degrees C ALD process was developed for GeOy using Ge(N(CH3)(2))(4) and H2O as precursors. In the ALD supercycle approach, the GeOy ALD cycle was interchanged with either ZnO or SnOy cycles to deposit TGO and ZGO with varying conduction band positions (Ec), respectively. The material properties were experimentally verified using X-ray photoelectron spectroscopy and optical absorption and by employing these films as ESLs in ACIGS solar cells. There, the open-circuit voltage initially increased as the Ge content of the TGO and ZGO films increased due to the ESL E-c simultaneously shifting up from the low position in ZnO or SnOy to match the ACIGS E-c. As the Ge content increased further, the fill factor (FF) of these devices decreased since the ESL E-c became positioned significantly above the ACIGS E-c, forming an energy barrier as seen from ACIGS. As a result, the efficiency of the ACIGS solar cell peaked for an intermediate Ge content for both TGO and ZGO. Using good TGO and ZGO compositions in ACIGS solar cells gave efficiencies of up to 14.8 and 17.0%, respectively, which were lower than the reference best cell efficiencies of up to 19.5% for CdS and 18.2% for Zn1-xSnxOy (ZTO). ZGO was, however, able to shift its Ec further up than ZTO, making it a potent ESL for high-band-gap absorbers. Based on the results, we listed a few key properties that are required for a good ACIGS solar cell ESL and gave a few suggestions on how they are linked to the previous success of ZTO.

Two inorganic electron-selective layers (ESLs), Sn1-xGexOy (TGO) and Zn1-xGexOy (ZGO), were developed by using atomic layer deposition (ALD) with in situ quartz crystal monitoring. To ensure (Ag,Cu)(In,Ga)Se-2 (ACIGS) solar cell compatibility, a 120 degrees C ALD process was developed for GeOy using Ge(N(CH3)(2))(4) and H2O as precursors. In the ALD supercycle approach, the GeOy ALD cycle was interchanged with either ZnO or SnOy cycles to deposit TGO and ZGO with varying conduction band positions (Ec), respectively. The material properties were experimentally verified using X-ray photoelectron spectroscopy and optical absorption and by employing these films as ESLs in ACIGS solar cells. There, the open-circuit voltage initially increased as the Ge content of the TGO and ZGO films increased due to the ESL E-c simultaneously shifting up from the low position in ZnO or SnOy to match the ACIGS E-c. As the Ge content increased further, the fill factor (FF) of these devices decreased since the ESL E-c became positioned significantly above the ACIGS E-c, forming an energy barrier as seen from ACIGS. As a result, the efficiency of the ACIGS solar cell peaked for an intermediate Ge content for both TGO and ZGO. Using good TGO and ZGO compositions in ACIGS solar cells gave efficiencies of up to 14.8 and 17.0%, respectively, which were lower than the reference best cell efficiencies of up to 19.5% for CdS and 18.2% for Zn1-xSnxOy (ZTO). ZGO was, however, able to shift its Ec further up than ZTO, making it a potent ESL for high-band-gap absorbers. Based on the results, we listed a few key properties that are required for a good ACIGS solar cell ESL and gave a few suggestions on how they are linked to the previous success of ZTO.

In this work, the use of poly (9,9-bis (30-(N,N-dimethylamino) propyl) -2,7-fluorene) -alt-2,7-(9,9-dioctylfluorene) (PFN) as electron transport layer (ETL) in inverted small molecule solar cells (SM-iOSCs) is analyzed. The optical and electrical characteristics obtained are compared with those obtained for similar SM-iOSCs where the ETL was zinc oxide. The p-DTS(FBTTh2)2 and PC70BM materials are used as donor and acceptor in the bulk heterojunction active layer, respectively for all devices. The photovoltaic devices exhibited a power conversion efficiency of 6.75% under 1 sun illumination. Impedance measurements were used to understand the causes that dominate the performance of the devices. We found that the loss resistance is governed by the PFN layer, which results in a lower fill factor value. Studies of atomic force microscopy, external quantum efficiency, and absorption UV-vis on the active layer have been performed to understand the effects of the charge transport dynamics on the performance of the devices.

This work demonstrates a simple yet effective method to significantly improve the power conversion efficiency (PCE) of highly efficient non-fullerene organic solar cells by mixing two electron transport materials. The new electron transport layer shows an energy level better aligned with the active layer and an improved morphology that could reduce the active layer−electrode contact. These improvements lead to enhanced charge extraction, better charge selectivity, suppressed exciton recombination, and finally a boosted PCE in the PM6:Y6- based solar cells. When applied in conjunction with the nonhalogenated solvent-processed PM6:PY-IT-based active layer, the mixed ETL also gives rise to a leading result for binary all-polymer solar cells (PCE of >16%) with a concurrent increase in VOC, JSC, and FF.

Semiconductor colloidal quantum rods (QRs) are evolving as potential candidates for future lighting and display applications due to numerous advantages. QRs offer various aids over quantum dots (QDs) in terms of polarized emission, large global Stokes shift, and double the outcoupling efficiency. In this paper, we synthesized CdSe/CdS/ZnS (core/shell/shell) green QRs with an emission wavelength at 520 nm and employed them in QR based light-emitting diodes (QRLEDs). The QRLED device performance was further optimized by inserting a thin poly (methyl methacrylate) (PMMA) layer in-between emissive layer and electron transport layer (ETL) (ZnO NP). The PMMA layer is acting as a barrier between the emissive layers to the ETL interface, and thus limit the excess electron injection into the QRs and helps to maintain the balanced charge injection. The fabricated green QRLEDs exhibit excellent optoelectronic performance, such as high brightness of 11890 cd/m2 and an impressive peak external quantum efficiency (EQE) of 5.6 %. Through further tuning the device with a PMMA, we elevated the peak-EQE up to 6.8%. To the best of our knowledge, these are the best-reported numbers for the QR based green light-emitting diodes.

Metal halide perovskite solar cells (PSCs) have attracted tremendous attention because of their rapid development. To enhance the power conversion efficiency (PCE) of PSCs, significant research efforts have focused on the optimization of electron transport layer (ETL). SnO2 has been extensively used as ETL due to its excellent electron transport properties. The optimization of the fabrication of SnO2 and passivation of the structural defects are essential to the improved performance of ETL. This thesis aims to (i) investigate the fabrication of pristine SnO2 thin film and characterize its material properties and (ii) develop a novel fabrication of reduced graphene oxide (RGO) modified SnO2 thin film as ETL and characterize its material properties.The first part was achieved by investigating the effects of UV-ozone treatment on fabrication of SnO2 thin films as well as the effects of precursor concentration and heating temperature on the resultant properties of the SnO2 thin films. The results showed that UV-ozone pretreatment is essential for depositing a continuous SnO2 thin film. A high precursor concentration resulted in low roughness and high n-type defects in SnO2 thin film, which would decrease the electrical conductivity while a high temperature of heat treatment resulted in increased crystallinity and a decrease in oxygen vacancies and residual Cl.The second part was achieved by investigating the effects of (i) preparation time of the RGO-SnO2 precursor and (ii) the concentration of RGO on the properties of RGO-SnO2 thin films. The RGO-SnO2 thin film was successfully fabricated by spin coating a precursor solution of SnCl2 in ethanol (95%) mixed with graphene oxide (GO) followed by heating at low temperatures. By conducting RGO modification, RGO-SnO2 thin films with high crystallinity and low oxygen vacancy contents were achieved resulting in a high electrical conductivity. The study showed that 3 h of preparation time for the precursor and addition amounts

[EN] Numerical analysis is a tool that is helping engineers over the past decades in design optimization and low-cost fabrication of solar cell devices. The need of modeling tools is used to deeply analyze a device in a soft environment where the time and cost both can be saved before putting a device into fabrication. In this study, lead iodide-based perovskite solar cells were modeled having several feasible planar pin structures for known electron and hole transport layers. The primarily taken pin device structure for analysis was PEDOT:PSS/MAPbI(3)(I)/PCBM. A total of seventy-two different structures were analyzed. From our results, thirty-seven devices have achieved a maximum efficiency of 21%. The best device structure has achieved a 23.29% PCE. Our proposed results can provide imperative guidelines to researchers for the design of efficient pin structure perovskite solar cells.

[EN] Numerical analysis is a tool that is helping engineers over the past decades in design optimization and low-cost fabrication of solar cell devices. The need of modeling tools is used to deeply analyze a device in a soft environment where the time and cost both can be saved before putting a device into fabrication. In this study, lead iodide-based perovskite solar cells were modeled having several feasible planar pin structures for known electron and hole transport layers. The primarily taken pin device structure for analysis was PEDOT:PSS/MAPbI(3)(I)/PCBM. A total of seventy-two different structures were analyzed. From our results, thirty-seven devices have achieved a maximum efficiency of 21%. The best device structure has achieved a 23.29% PCE. Our proposed results can provide imperative guidelines to researchers for the design of efficient pin structure perovskite solar cells.

This work demonstrates a simple yet effective method to significantly improve the power conversion efficiency (PCE) of highly efficient non-fullerene organic solar cells by mixing two electron transport materials. The new electron transport layer shows an energy level better aligned with the active layer and an improved morphology that could reduce the active layer−electrode contact. These improvements lead to enhanced charge extraction, better charge selectivity, suppressed exciton recombination, and finally a boosted PCE in the PM6:Y6- based solar cells. When applied in conjunction with the nonhalogenated solvent-processed PM6:PY-IT-based active layer, the mixed ETL also gives rise to a leading result for binary all-polymer solar cells (PCE of >16%) with a concurrent increase in VOC, JSC, and FF.

Semiconductor colloidal quantum rods (QRs) are evolving as potential candidates for future lighting and display applications due to numerous advantages. QRs offer various aids over quantum dots (QDs) in terms of polarized emission, large global Stokes shift, and double the outcoupling efficiency. In this paper, we synthesized CdSe/CdS/ZnS (core/shell/shell) green QRs with an emission wavelength at 520 nm and employed them in QR based light-emitting diodes (QRLEDs). The QRLED device performance was further optimized by inserting a thin poly (methyl methacrylate) (PMMA) layer in-between emissive layer and electron transport layer (ETL) (ZnO NP). The PMMA layer is acting as a barrier between the emissive layers to the ETL interface, and thus limit the excess electron injection into the QRs and helps to maintain the balanced charge injection. The fabricated green QRLEDs exhibit excellent optoelectronic performance, such as high brightness of 11890 cd/m2 and an impressive peak external quantum efficiency (EQE) of 5.6 %. Through further tuning the device with a PMMA, we elevated the peak-EQE up to 6.8%. To the best of our knowledge, these are the best-reported numbers for the QR based green light-emitting diodes.

This work demonstrates a simple yet effective method to significantly improve the power conversion efficiency (PCE) of highly efficient non-fullerene organic solar cells by mixing two electron transport materials. The new electron transport layer shows an energy level better aligned with the active layer and an improved morphology that could reduce the active layer−electrode contact. These improvements lead to enhanced charge extraction, better charge selectivity, suppressed exciton recombination, and finally a boosted PCE in the PM6:Y6- based solar cells. When applied in conjunction with the nonhalogenated solvent-processed PM6:PY-IT-based active layer, the mixed ETL also gives rise to a leading result for binary all-polymer solar cells (PCE of >16%) with a concurrent increase in VOC, JSC, and FF.

Semiconductor colloidal quantum rods (QRs) are evolving as potential candidates for future lighting and display applications due to numerous advantages. QRs offer various aids over quantum dots (QDs) in terms of polarized emission, large global Stokes shift, and double the outcoupling efficiency. In this paper, we synthesized CdSe/CdS/ZnS (core/shell/shell) green QRs with an emission wavelength at 520 nm and employed them in QR based light-emitting diodes (QRLEDs). The QRLED device performance was further optimized by inserting a thin poly (methyl methacrylate) (PMMA) layer in-between emissive layer and electron transport layer (ETL) (ZnO NP). The PMMA layer is acting as a barrier between the emissive layers to the ETL interface, and thus limit the excess electron injection into the QRs and helps to maintain the balanced charge injection. The fabricated green QRLEDs exhibit excellent optoelectronic performance, such as high brightness of 11890 cd/m2 and an impressive peak external quantum efficiency (EQE) of 5.6 %. Through further tuning the device with a PMMA, we elevated the peak-EQE up to 6.8%. To the best of our knowledge, these are the best-reported numbers for the QR based green light-emitting diodes.

Defects passivation in electron transport layer (ETL) is a key issue to optimize the performance of polymer solar cells (PSCs). In this work, a novel strategy is developed to form defects passivated ZnO ETL by introducing 4-tert-butylpyridine (TBP) agent into precursor. While the power conversion efficiency (PCE) of the inverted PSCs based poly{4,8-bis [(2-ethylhexyl)oxy]benzo [1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno [3,4-b]thiophene-4,6-diyl}:[6,6]-phenyl C71-butyric acid methyl ester (PTB7:PC71BM) with the pure ZnO ETL is 8.02%, that of the device with modified ZnO ETL is dramatically improved to 10.26%, with TBP accounting for ~28% efficiency improvement. Our study demonstrates that the precursor agent significantly affect the surface morphology and size of ZnO in ETL. Furthermore, it proves that the ZnO ETL with TBP (T-ZnO) is beneficial to polish interfacial contact between ETL and active layer and depress exciton quenching loss, resulting in enhanced exciton dissociation, efficient carrier collection and reduced charge recombination, thus improving the device performance. To verify the universality of T-ZnO ETL, the champion photovoltaic performance with a PCE of 11.74% (10% improvement) is obtained in the PBDB-T-2F:IT-4F based nonfullerene PSCs using T-ZnO as ETL. Our work developed a new, universal and facile strategy for designing highly efficient PSCs based on fullerene and nonfullerene blend systems. © 2019 Elsevier B.V.

Defects passivation in electron transport layer (ETL) is a key issue to optimize the performance of polymer solar cells (PSCs). In this work, a novel strategy is developed to form defects passivated ZnO ETL by introducing 4-tert-butylpyridine (TBP) agent into precursor. While the power conversion efficiency (PCE) of the inverted PSCs based poly{4,8-bis [(2-ethylhexyl)oxy]benzo [1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno [3,4-b]thiophene-4,6-diyl}:[6,6]-phenyl C71-butyric acid methyl ester (PTB7:PC71BM) with the pure ZnO ETL is 8.02%, that of the device with modified ZnO ETL is dramatically improved to 10.26%, with TBP accounting for ~28% efficiency improvement. Our study demonstrates that the precursor agent significantly affect the surface morphology and size of ZnO in ETL. Furthermore, it proves that the ZnO ETL with TBP (T-ZnO) is beneficial to polish interfacial contact between ETL and active layer and depress exciton quenching loss, resulting in enhanced exciton dissociation, efficient carrier collection and reduced charge recombination, thus improving the device performance. To verify the universality of T-ZnO ETL, the champion photovoltaic performance with a PCE of 11.74% (10% improvement) is obtained in the PBDB-T-2F:IT-4F based nonfullerene PSCs using T-ZnO as ETL. Our work developed a new, universal and facile strategy for designing highly efficient PSCs based on fullerene and nonfullerene blend systems. © 2019 Elsevier B.V.

Organic–inorganic hybrid perovskite solar cells have attracted much attention due to their high power conversion efficiency (>25%) and low-cost fabrication. Yet, improvements are still needed for more stable and higher-performing solar cells. In this work, a series of TiO2 nanocolumn photonic structures have been intentionally fabricated on half of the compact TiO2-coated fluorine-doped tin oxide substrate by glancing angle deposition with magnetron sputtering, a method particularly suitable for industrial applications due to its high reliability and reduced cost when coating large areas. These vertically aligned nanocolumn arrays were then applied as the electron transport layer into triple-cation lead halide perovskite solar cells based on Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3. By comparison to solar cells built onto the same substrate without nanocolumns, the use of TiO2 nanocolumns can significantly enhance the power conversion efficiency of the perovskite solar cells by 7% and prolong their shelf life. Here, detailed characterizations on the morphology and the spectroscopic aspects of the nanocolumns, their near-field and far-field optical properties, solar cells characteristics, as well as the charge transport properties provide mechanistic insights on how one-dimensional TiO2 nanocolumns affect the performance of perovskite halide solar cells in terms of charge transport, light harvesting, and stability, knowledge necessary for the future design of higher-performing and more stable perovskite solar cells.

This project is to find innovative and alternate Nano-sized materials for solar energy applications. This include conversion of solar light energy into electricity or generate clean environment friendly fuels by breaking water into Oxygen and Hydrogen. The study has explored material characteristics at electronic level to reveal new properties. These revelations then compared amongst some of the organic and inorganic materials for the intended purpose. Innovative design of new carbon-compounds (termed as carbon Quantum dots) included in the study for use in the new generation Perovskite solar cells for charge transfer.

This research presents thin film deposition and characterization of metal oxides using industrially viable Physical Vapour Deposition (PVD) techniques. The research examines low temperature processed electron and hole transport metal oxides for high performance and stable perovskite solar cells. The physical, chemical, optical and electronic properties of the films were investigated and their device performance has been evaluated. The performance of the device improved and the materials cost reduced by replacing the expansive organic materials with more stable inorganic metal oxides.

type:Journal Article, TiO2 is commonly used as an electron-transporting material in perovskite photovoltaic devices due to its advantages, including suitable band gap, good photoelectrochemical stability, and simple preparation process. However, there are many oxygen vacancies or defects on the surface of TiO2 and thus this affects the stability of TiO2-based perovskite solar cells under UV light. In this work, a thin (monolayer) SbI3 modification layer is introduced on the mesoporous TiO2 surface and the effect at the interface between of TiO2 and perovskite is monitored by using a quartz crystal microbalance system. We demonstrate that the SbI3-modified TiO2 electrodes exhibit superior electronic properties by reducing electronic trap states, enabling faster electron transport. This approach results in higher performances compared with electrodes without the SbI3 passivation layer. CH3NH3PbI3 perovskite solar cells with a maximum power conversion efficiency of 17.33% in air, accompanied by a reduction in hysteresis and enhancement of the device stability, are reported., source:DOI:10.1021/acsami.8b10062

Stability and scalability have become the two main challenges for perovskite solar cells (PSCs) with the research focus in the field advancing toward commercialization. One of the prerequisites to solve these challenges is to develop a cost-effective, uniform, and high quality electron transport layer that is compatible with stable PSCs. Sputtering deposition is widely employed for large area deposition of high quality thin films in the industry. Here the composition, structure, and electronic properties of room temperature sputtered SnO2 are systematically studied. Ar and O-2 are used as the sputtering and reactive gas, respectively, and it is found that a highly oxidizing environment is essential for the formation of high quality SnO2 films. With the optimized structure, SnO2 films with high quality have been prepared. It is demonstrated that PSCs based on the sputtered SnO2 electron transport layer show an efficiency up to 20.2% (stabilized power output of 19.8%) and a T-80 operational lifetime of 625 h. Furthermore, the uniform and thin sputtered SnO2 film with high conductivity is promising for large area solar modules, which show efficiencies over 12% with an aperture area of 22.8 cm(2) fabricated on 5 x 5 cm(2) substrates (geometry fill factor = 91%), and a T-80 operational lifetime of 515 h.

In the present article, the detailed analyses of interface properties and device performance of inorganic perovskite CaMnO3-based buffer layer hybrid perovskite solar cell have been undertaken. Analyses are based on ab initio simulations and macroscopic modelling. A thorough study of electronic and optical properties and interface charge dynamics revealed that CaMnO3 presents a better candidate for the electron transport material in thin film hole transporting material free hybrid perovskite solar cells with the planar architecture than the most common anatase TiO2. This result is founded on the more appropriate band gap and better band alignment with the hybrid perovskite, leading to the faster charge carrier mobility, improved charge transfer and reduced exciton recombination. The results from theoretical simulations are justified by the solar cell model, which explored the basic cell characteristics and parameters: open circuit voltage, short circuit current, fill factor and efficiency, as the functions of cell performance factors, like defect density, diffusion length, absorber layer thickness and band offset. Our model suggests an unoptimized device with a photo-conversion efficiency of almost 10% for the low defect concentrations under 10(15). With efficiency in the upper range for HTM free perovskite solar cells, we propose that the CaMnO3-based solar cell poses as an improvement upon the up to now most frequently used ones and provides important step toward their commercialisation.

In this paper, we report enhanced performance of inverted polymer solar cells composed of poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1):[6,6]-phenyl-C-71-butyric acid methyl ester (PC71BM) blends by using poly(ethylene oxide) (PEO)-modified ZnO as an electron transport layer. It is found that PEO modification to the ZnO nanoparticle surface can effectively passivate the surface traps of ZnO, suppress the recombination loss of carriers, reduce the series resistance, and improve the electrical coupling of ZnO/active layer. Consequently, both the short-circuit current (J(SC)) and the fill factor (FF) of the inverted solar cells are considerably improved. The resulting power conversion efficiency (PCE) is improved to 5.64% as compared to 4.5% of the reference device using a ZnO electron transport layer. Moreover, this approach can also successfully improve the J(SC) and FF of anther inverted solar cell composed of poly[N-9 -hepta-decanyl-2,7-carbazole-alt-5,5-(4,7-dithienyl-2,1,3-benzothiadiazole)] (PCDTBT):PC71BM blends. The PCE of the device based on the PEO-modified ZnO layer is increased to 6.59% from 5.39% of the reference device based on the ZnO layer., Funding Agencies|Swedish energy agency (Energimyndigheten)||Swedish Research Council (VR)||Knut, Alice Wallenberg Foundation||Crafoord foundation||VINNOVA