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Faormamadinium based perovskites have been proposed to replace the methylammonium lead tri-iodide (MAPbI3) perovskite as the light absorbing layer of photovoltaic cells owing to their photo-active and chemically stable properties. However, the crystal phase transition from the photo-active α -FAPbI3 to the non-perovksite δ -FAPbI3 still occurs in un-doped FAPbI3 films owing to the existence of crack defects, which degrads the photovoltaic responses. To investigate the crack ratio (CR)-dependent structure and excitonic characteristics of the polycrystalline FAPbI3 thin films deposited on the carboxylic acid functionalized ITO/glass substrates, various spectra and images were measured and analyzed, which can be utilized to make sense of the different devices responses of the resultant perovskite based photovoltaic cells. Our experimental results show that the there is a trade-off between the formations of surface defects and trapped iodide-mediated defects, thereby resulting in an optimal crack density or CR of the un-doped α -FAPbI3 active layer in the range from 4.86% to 9.27%. The decrease in the CR (tensile stress) results in the compressive lattice and thereby trapping the iodides near the PbI6 octahedra in the bottom region of the FAPbI3 perovskite films. When the CR of the FAPbI3 film is 8.47%, the open-circuit voltage (short-circuit current density) of the resultant photovoltaic cells significantly increased from 0.773 V (16.62 mA cm−2) to 0.945 V (18.20 mA cm−2) after 3 d. Our findings help understanding the photovoltaic responses of the FAPbI3 perovskite based photovoltaic cells on the different days. [ABSTRACT FROM AUTHOR]

Buttcoupling is the most efficient way to excite surface plasmon polariton (SPP) waves at dielectric/metal interfaces in order to realize applications in broadband and ultra-compact integrated circuits (IOCs). We propose a reasonable waveguide structure to efficiently excite and collect the SPP waves supported in a plasmonic trench waveguide in the long-haul telecommunication wavelength range. Our simulation results show that the coupling efficiency between the dielectric strip waveguides and a plasmonic trench waveguide can be optimized, which is dominated by the zigzag propagation path length in the dielectric strip loaded on the metal substrate. It is noted that nearly a 100% coupling efficiency can be achieved when the distance between the excitation source and the plasmonic waveguide is about 6.76 μm. [ABSTRACT FROM AUTHOR]

The properties of CH3NH3PbI3 (MAPbI3) crystalline thin films and the device performance of highly efficient MAPbI3 photovoltaic cells are investigated by varying the temperature of the antisolvent from 20 °C to 50 °C during the washing enhanced nucleation (WEN) process. The surface, structural, optoelectronic and defect properties of the perovskite thin films are characterized through atomic-force microscopy, X-ray diffractometry and photoluminescence spectrometry. The experimental results show that changing the temperature of the antisolvent during the WEN process can manipulate the MAPbI3 crystalline thin films from the (110)â€"(002) complex phase to a (002) preferred phase. It is noted that the highest power conversion efficient of the inverted MAPbI3 photovoltaic cells is 19.30%, mainly due to the increased carrier collection efficiency and reduced carrier recombination when the temperature of the antisolvent is 30 °C. [ABSTRACT FROM AUTHOR]

The surface morphologies, crystallinities, and excitonic characteristics of MAxCs1−xPb(IxBr1−x)3 thin films deposited on top of the P3CT‐Na/ITO/glass substrates are investigated by using the atomic‐force microscopic images, absorbance spectra, grazing incidence X‐ray diffraction patterns, photoluminescence (PL) spectra, and Raman scattering spectra. The P3CT‐Na‐based perovskite solar cell shows a stable and efficient maximum power density curve due to the formation of a graded MA0.83Cs0.17Pb(I0.83Br0.17)3 alloy thin film which is confirmed by using the surface‐sensitive PL and Raman scattering spectra. The highest power conversion efficiency (PCE) of the P3CT‐Na‐based MA0.83Cs0.17Pb(I0.83Br0.17)3 solar cells is 15.93% mainly due to the high fill factor of 79.4%. Besides, the PCE of the nonencapsulated solar cell slowly decreases to a moderate value (10.48%) within 157 days under an uncontrolled environment (55–60 relative humidity%) at room temperatures (22–25 °C). [ABSTRACT FROM AUTHOR]

Atomic-force microscopic images, x-ray diffraction patterns, Urbach energies and photoluminescence quenching experiments show that the interfacial contact quality between the hydrophobic [6,6]-phenyl-C61-buttric acid methyl ester (PCBM) thin film and hydrophilic CH3NH3PbI3 (MAPbI3) thin film can be effectively improved by using a binary antisolvent mixture (toluene:dichloromethane or chlorobenzene:dichloromethane) in the anti-solvent mixture-mediated nucleation process, which increases the averaged power conversion efficiency of the resultant PEDOT:PSS (P3CT-Na) thin film based MAPbI3 solar cells from 13.18% (18.52%) to 13.80% (19.55%). Beside, the use of 10% dichloromethane (DCM) in the binary antisolvent mixture results in a nano-textured MAPbI3 thin film with multicrystalline micrometer-sized grains and thereby increasing the short-circuit current density and fill factor (FF) of the resultant solar cells. It is noted that a remarkable FF of 80.33% is achieved, which can be used to explain the stable photovoltaic performance without additional encapsulations. [ABSTRACT FROM AUTHOR]

The averaged power conversion efficiency of polyelectrolytes (P3CT-Na) based MAPbI3 solar cells can be increased from 14.94% to 17.46% with a wetting method before the spin-coating process of MAPbI3 precursor solutions. The effects of the wetting process on the surface, structural, optical and excitonic properties of MAPbI3 thin films are investigated by using the atomic-force microscopic images, x-ray diffraction patterns, transmittance spectra, photoluminescence spectra and Raman scattering spectra. The experimental results show that the wetting process of MAPbI3 precursor solution on top of the P3CT-Na/ITO/glass substrate can be used to manipulate the molecular packing structure of the P3CT-Na thin film, which determines the formation of MAPbI3 thin films. [ABSTRACT FROM AUTHOR]

A high-efficiency inverted-type CH3NH3PbI3 (MAPbI3) solar cell was fabricated by using a ultrathin poly[3-(4-carboxybutyl)thiophene-2,5-diyl]-Na (P3CT-Na) film as the hole transport layer. The averaged power conversion efficiency (PCE) can be largely increased from 11.72 to 18.92% with a double-filtering process of the P3CT-Na solution mainly due to the increase in short-circuit current density (JSC) from 19.43 to 23.88 mA/cm2, which means that the molecular packing structure of P3CT-Na thin film can influence the formation of the MAPbI3 thin film and the contact quality at the MAPbI3/P3CT-Na interface. Zeta potentials, atomic-force microscopic images, absorbance spectra, photoluminescence spectra, X-ray diffraction patterns, and Raman scattering spectra are used to understand the improvement in the JSC. Besides, the light intensity-dependent and wavelength-dependent photovoltaic performance of the MAPbI3 solar cells shows that the P3CT-Na thin film is not only used as the hole transport layer but also plays an important role during the formation of a high-quality MAPbI3 thin film. It is noted that the PCE values of the best P3CT-Na based MAPbI3 solar cell are higher than 30% in the yellow-to-near infrared wavelength range under low light intensities. On the other hand, it is predicted that the double-filtering method can be readily used to increase the PCE of polymer based solar cells. [ABSTRACT FROM AUTHOR]

The power conversion efficiency (PCE) of single-junction solar cells was theoretically predicted to be limited by the Shockley–Queisser limit due to the intrinsic potential loss of the photo-excited electrons in the light absorbing materials. Up to now, the optimized GaAs solar cell has the highest PCE of 29.1%, which is close to the theoretical limit of ~33%. To pursue the perfect photovoltaic performance, it is necessary to extend the lifetimes of the photo-excited carriers (hot electrons and hot holes) and to collect the hot carriers without potential loss. Thanks to the long-lived hot carriers in perovskite crystal materials, it is possible to completely convert the photon energy to electrical power when the hot electrons and hot holes can freely transport in the quantized energy levels of the electron transport layer and hole transport layer, respectively. In order to achieve the ideal PCE, the interactions between photo-excited carriers and phonons in perovskite solar cells has to be completely understood. [ABSTRACT FROM AUTHOR]

Faormamadinium based perovskites have been proposed to replace the methylammonium lead tri-iodide (MAPbI 3 ) perovskite as the light absorbing layer of photovoltaic cells owing to their photo-active and chemically stable properties. However, the crystal phase transition from the photo-active α -FAPbI 3 to the non-perovksite δ -FAPbI 3 still occurs in un-doped FAPbI 3 films owing to the existence of crack defects, which degrads the photovoltaic responses. To investigate the crack ratio (CR)-dependent structure and excitonic characteristics of the polycrystalline FAPbI 3 thin films deposited on the carboxylic acid functionalized ITO/glass substrates, various spectra and images were measured and analyzed, which can be utilized to make sense of the different devices responses of the resultant perovskite based photovoltaic cells. Our experimental results show that the there is a trade-off between the formations of surface defects and trapped iodide-mediated defects, thereby resulting in an optimal crack density or CR of the un-doped α -FAPbI 3 active layer in the range from 4.86% to 9.27%. The decrease in the CR (tensile stress) results in the compressive lattice and thereby trapping the iodides near the PbI 6 octahedra in the bottom region of the FAPbI 3 perovskite films. When the CR of the FAPbI 3 film is 8.47%, the open-circuit voltage (short-circuit current density) of the resultant photovoltaic cells significantly increased from 0.773 V (16.62 mA cm -2 ) to 0.945 V (18.20 mA cm -2 ) after 3 d. Our findings help understanding the photovoltaic responses of the FAPbI 3 perovskite based photovoltaic cells on the different days., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

The grain sizes of soft CH 3 NH 3 PbI 3 (MAPbI 3 ) thin films and the atomic contact strength at the MAPbI 3 /P3CT-Na interface are manipulated by varying the drying time of the saturated MAPbI 3 precursor solutions, which influences the device performance and lifespan of the resultant inverted perovskite photovoltaic cells. The atomic-force microscopy images, cross-sectional scanning electron microscopy images, photoluminescence spectra and absorbance spectra show that the increased short-circuit current density ( J SC ) and increased fill factor (FF) are mainly due to the formation of merged MAPbI 3 grains. Besides, the open-circuit voltage ( V OC ) of the encapsulated photovoltaic cells largely increases from 1.01 V to 1.15 V, thereby increasing the power conversion efficiency from 17.89% to 19.55% after 30 days, which can be explained as due to the increased carrier density of the MAPbI 3 crystalline thin film. It is noted that the use of the optimized drying time during the spin coating process results in the formation of merged MAPbI 3 grains while keeping the contact quality at the MAPbI 3 /P3CT-Na interface, which boosts the device performance and lifespan of the resultant perovskite photovoltaic cells., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The properties of CH 3 NH 3 PbI 3 (MAPbI 3 ) crystalline thin films and the device performance of highly efficient MAPbI 3 photovoltaic cells are investigated by varying the temperature of the antisolvent from 20 °C to 50 °C during the washing enhanced nucleation (WEN) process. The surface, structural, optoelectronic and defect properties of the perovskite thin films are characterized through atomic-force microscopy, X-ray diffractometry and photoluminescence spectrometry. The experimental results show that changing the temperature of the antisolvent during the WEN process can manipulate the MAPbI 3 crystalline thin films from the (110)-(002) complex phase to a (002) preferred phase. It is noted that the highest power conversion efficient of the inverted MAPbI 3 photovoltaic cells is 19.30%, mainly due to the increased carrier collection efficiency and reduced carrier recombination when the temperature of the antisolvent is 30 °C., (© 2022 IOP Publishing Ltd.)

Atomic-force microscopic images, x-ray diffraction patterns, Urbach energies and photoluminescence quenching experiments show that the interfacial contact quality between the hydrophobic [6,6]-phenyl-C 61 -buttric acid methyl ester (PCBM) thin film and hydrophilic CH 3 NH 3 PbI 3 (MAPbI 3 ) thin film can be effectively improved by using a binary antisolvent mixture (toluene:dichloromethane or chlorobenzene:dichloromethane) in the anti-solvent mixture-mediated nucleation process, which increases the averaged power conversion efficiency of the resultant PEDOT:PSS (P3CT-Na) thin film based MAPbI 3 solar cells from 13.18% (18.52%) to 13.80% (19.55%). Beside, the use of 10% dichloromethane (DCM) in the binary antisolvent mixture results in a nano-textured MAPbI 3 thin film with multicrystalline micrometer-sized grains and thereby increasing the short-circuit current density and fill factor (FF) of the resultant solar cells. It is noted that a remarkable FF of 80.33% is achieved, which can be used to explain the stable photovoltaic performance without additional encapsulations., (© 2021 IOP Publishing Ltd.)

The averaged power conversion efficiency of polyelectrolytes (P3CT-Na) based MAPbI 3 solar cells can be increased from 14.94% to 17.46% with a wetting method before the spin-coating process of MAPbI 3 precursor solutions. The effects of the wetting process on the surface, structural, optical and excitonic properties of MAPbI 3 thin films are investigated by using the atomic-force microscopic images, x-ray diffraction patterns, transmittance spectra, photoluminescence spectra and Raman scattering spectra. The experimental results show that the wetting process of MAPbI 3 precursor solution on top of the P3CT-Na/ITO/glass substrate can be used to manipulate the molecular packing structure of the P3CT-Na thin film, which determines the formation of MAPbI 3 thin films., (© 2021 IOP Publishing Ltd.)