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The grain sizes of MAPbI3 films and the atomic contact strength at the MAPbI3/P3CT-Na interface are manipulated by varying the drying time of saturated MAPbI3 precursor solutions, which influences the performance of the resultant perovskite photovoltaic cells.

The conformal loading effects of P3CT-Na polymers on ITO/glass samples were investigated using different concentrations of P3TC-Na/water solution, which significantly influenced the device efficiency of the resultant inverted perovskite solar cells. The obtained water-droplet contact angle images, surface morphological images, photoluminescence spectra and X-ray diffraction patterns show that the hydrophilic moiety of the P3CT-Na polymers plays an important role in the conformal loading effects, thereby resulting in a smoother perovskite crystalline film due to the formation of merged grains. It is noted that the average power conversion efficiency increases from 14.83% to 17.27% with a decrease in the concentration of the P3CT-Na/water solution from 60 wt% to 48 wt%.

The s-shaped J-V curve of perovskite solar cells can be eliminated using the solvent penetration (SP) process with a PCBM spacer. The experimental results show that the viscosity of the solvent used in the SP process influences the shunt and series resistances simultaneously. In addition, the fill factor of PEDOT:PSS based perovskite solar cells can be largely increased from 40.3% to 70.7% when the bathocuproine (BCP) molecules are dissolved in IPA solvent during the SP process, which significantly increases the power conversion efficiency (PCE) by 98.9%. Besides, the PCE of perovskite solar cells increases from 13.56% to 20.29% when the PEDOT:PSS film is replaced by a P3CT-Na thin film. It is noted that the absorbance spectra, photoluminescence (PL) spectra, time-resolved PL, Raman spectra and X-ray diffraction patterns demonstrate that the BCP molecules penetrate into the PCBM thin film and the PCBM/perovskite interface during the SP process, which increases the electron mobility of the PCBM thin film and passivates the interfacial MA cations in perovskite thin film, respectively. In other words, the solution-processed BCP small molecules are vertically distributed across the PCBM thin film. Our results help completely understand the entire roles of the solution-processed BCP molecules in the high-performance inverted-type perovskite solar cells.

Sub-wavelength TiO2 nanospheres arranged in a two-dimensional (2D) square array and a 2D hexagonal array are used to increase the light-extraction efficiency of an air/GaN interface, which is theoretically investigated by using the finite-different time-domain method. The simulation results show that the 3-dB bandwidth of light extraction can be largely increased from 29 nm to 121 nm when the coupled periodically electric quadrupoles (CPEQ) is supported in a 2D square array. In addition, the near critical coupling of 99.4% can be achieved at the wavelength of 735 nm when the gap distance between adjacent TiO2 nanospheres is 110 nm. The manipulation of field orthogonality between the electric and magnetic fields results in an increase in the bandwidth of CPEQ, which plays an important role for the ultra-broadband and efficient light extraction.

High-impurity precursor based CH3NH3PbI3 (MAPbI3) perovskite thin films are fabricated by using the one-step spin-coating method with an anti-solvent mixture-mediated nucleation (ASMEN) process under various dropping times. The structural, optical and excitonic properties of the resultant perovskite thin films are characterized through the X-ray diffractometer, absorbance spectrometer, photoluminescence spectrometer and Raman scattering spectrometer. The experimental results show that the dropping time and the use of 10% dicloromethane (DCM) in the ASMEN process strongly influences the formation of point defects in the resultant MAPbI3 thin film, which dominates the current-hysteresis behavior in the current density-voltage curves of solar cells. In addition, this investigation helps further understand the effects of toluene/DCM anti-solvent mixture on the formation of point defect-free MAPbI3 thin films.

Deterioration of indoor air quality (IAQ) has become a serious concern as people spend lots of time indoors and prolonged pollution exposure can result in adverse health outcomes. Indoor plants can phytoremediate a wide variety of indoor contaminants. Nonetheless, few experiments have demonstrated their efficacy in real-time environments. Therefore, the present study aims to experimentally assess the efficiency of Areca palm potted plants in phytoremediation of primary indoor air pollutant viz. total volatile organic compounds (TVOCs), carbon dioxide (CO2), and carbon monoxide (CO) levels from real-world indoor spaces, for the first time. Four discrete naturally ventilated experimental sites (I-IV) situated at the Council of Scientific and Industrial Research- Institute of Himalayan Bioresource Technology (CSIR-IHBT) were used. For over a period of 4 months, the sites were monitored using zero plants as a control (1–4 week), three plants (5–8 week), six plants (9–12 week), and nine plants (13–16 week), respectively. Present results indicate that Areca palm potted plants can effectively reduce the TVOCs, CO2, and CO levels by 88.16% in site IV, 52.33% and 95.70% in site III, respectively. The current study concluded that Areca palm potted plants offer an efficient, cost-effective, self-regulating, sustainable solution for improving indoor air quality and thereby human well-being and productivity in closed and confined spaces.

We report on an efficient solar-heat shield based on the highly transparent PEDOT:PSS thin film, which significantly reduces the temperature from 38.2 C to 33.5 C. To understand the superior solar-heat shielding ability, the modified PEDOT:PSS thin films were investigated by using the transmittance spectra, Raman scattering spectra, atomic-force microscopic (AFM) images and broadband refractive index spectra. The experimental results show that the molecular structure of the PEDOT chains can be manipulated by varying the Brownian motion of PEDOT polymers in the PEDOT:PSS solutions and the spin rate. The lower Brownian motion of PEDOT polymers and the higher spin rate both can change the molecular structure of the PEDOT chains from bended structures (de-doping states) to linear structures (doping states), which simultaneously increase the near-infrared absorption strength and the visible transparency due to the formation of bipolarons.

The properties of CH

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

The averaged power conversion efficiency of polyelectrolytes (P3CT-Na) based MAPbI

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.

Transmittance spectra, atomic-force microscopic images, energy-dispersive X-ray spectra and droplet contact angle images show that a facile wet etching process can be used to manipulate the thickness, surface roughness, surface chemical composition and surface wettability of the indium-tin oxide (ITO) thin films, which influences the molecular packing structure of the P3CT-Na thin films and thereby dominating the crystal quality of the CH3NH3PbI3 (MAPbI3) thin films. The power conversion efficiency (PCE) of the P3CT-Na based MAPbI3 solar cells can be improved from 17.02% to 19.35% by increasing the Sn/In concentration ratio of the ITO thin films from 0.36 to 0.47 with a facile wet etching process at a constant temperature of 40 °C. It is noted that the PCE of the optimal solar cell decreases slowly toward a stable PCE of 16% for more than 60 days under moderate environment conditions (55 ± 10 RH%).

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 MAPbI3solar 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 MAPbI3thin 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.

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.

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.

An Ag modified bathocuproine:ZnO nanoparticles (BCP:ZnO NPs) thin film was used as the buffer layer of inverted-type perovskite solar cells, which increased the bifacial power conversion efficiency from 6.82% to 15.50%. The surface-enhanced Raman scattering and absorbance spectra show that the Ag modified BCP small molecules can effectively passivate the surface oxygen defects of ZnO NPs and thereby increasing the crystallinity, which simultaneously increases the short-circuit current density (JSC) and fill factor. It is noted that a high incident photon-to-electron conversion efficiency (IPCE) of 92% is achieved at the wavelength of 587 nm due to the constructive interference effect in the multilayer structure, which can be used to explain the high photocurrent generation in a semi-transparent solar cell. In addition, the light intensity-dependent experimental results of the bifacial perovskite solar demonstrates that the hole transportation is better than the electron transportation in the perovskite thin film. This concept can be readily used in the optimization of high-efficiency bifacial perovskite solar cells.