The light and shade of perovskite solar cells.

Lead-free tin perovskite solar cells

Organometal hybrid perovskite material has emerged as an attractive competitor in the field of photovoltaics due to its promising potential of low-cost and high-efficiency photovoltaic applications. Although organometal halide perovskite solar cell shows great potential to meet future energy needs, the degradation raises serious questions about its commercialization viability. At present, the stability of perovskite solar cells has been studied in various environmental conditions. Nonetheless, an understanding of the degradation and its performance of CH3NH3PbI3-xClx perovskite solar cell is limited. Herein, we report the mechanical and structural degradation of CH3NH3PbI3-xClx perovskite films at room temperature as a function of time and thermal instability of perovskite solar cells during the heating and cooling processes. For mechanical degradation measurement, we used nanoindentation for CH3NH3PbI3-xClx perovskite films fabricated on FTO/PEDOT:PSS substrate. The hardness and elastic modulus of perovskite films were measured as a function of time. In addition, the mechanical degradation of perovskite thin films was correlated with X-ray diffraction, steady-state and time-resolved photoluminescence (PL). We also investigated the thermal instability of perovskite thin films and the irreversible performance of perovskite solar cells. Particularly, the irreversible performance of CH3NH3PbI3-xClx was analyzed by measuring the development of crystallinity, charge trapping/detrapping, trap depth, and PbI- phase while varying the temperature of perovskite films and solar cells between room temperature and 82 °C. Surprisingly, we found that the degradation of both perovskite films and solar cells occurred at ~70°C. Remarkably, even after the perovskite solar cell temperature cooled down to room temperature, the performance of solar cells continuously degraded. The underlying mechanism of irreversibly degraded performance of perovskite films and solar cells were explained in terms of the development of phase separation, increased trapping rates and deep trap depth of defect states of perovskite films.

An analysis comparing the performance of lead and tin halides organic Perovskite Solar Cells and numerical simulation with SCAPS

The absorbing layer thickness is a crucial parameter that significantly impacts the performance of perovskite solar cells (PSCs). In this study, we investigated the influence of the thickness of absorbing layer on the performance of silver-doped NaZnBr3 perovskite solar cells using the one-dimensional solar cell capacitance simulator (SCAPS-1D) software. The absorbing layer thickness was varied in the range of 0.1 to 1.3 µm. The initial solar cell after simulation gave an open-circuit voltage (Voc) of 1.174 V, short circuit current density (Jsc) of 14.012 mA/cm2, fill factor (FF) of 79.649%, and the power conversion efficiency (PCE) of 13.101%. For the optimized thickness of the perovskite layer of 1.0 µm, the following solar cell characteristics were obtained: Voc = 1.197 V, Jsc = 18.184 mA·cm–2, FF = 79.110%, and PCE = 17.215%. A 31% and 30% increase of the PCE and Jsc, respectively, was observed for the optimized device parameters as compared to the initial ones. Such finding confirms the premise for excellent photon management and enhancement of PSCs performance by selecting the thickness of absorbing layer.

Enhancing photovoltaic performance of carbon-based perovskite solar cells by introducing plasmonic Au NPs

Hole transport layer is of vital important for improving the photo-to-electron efficiency of perovskite solar cells. In this study, we investigate the performance of meso-structure perovskite solar cell applying bilayer materials for improving hole extraction ability. By simulating the performance of perovskite solar cell using wxAMPS software, CuOx is chosen to be ideal candidate of inorganic hole transport material which can moderate device property. The optimized value band offset in schematic diagram shows that photo-generated holes could be extracted from perovskite layer to spiro-OMeTAD efficiently by applying CuOx layer at the interface of perovskite/spiro-OMeTAD. Moreover, the experiment results show that Jsc of device increase to 19.5 mA/cm2, FF increase to 65.9% and total PCE reaches 12.3% by adopting CuOx/spiro-OMeTAD bilayer as hole transfer layer. Simultaneously, hysteresis decreases from 2% to 0.7% and integrated Jsc increase from 14.8 mA/cm2 to 16.03 mA/cm2. The PL results also confirm the mechanism of carrier extraction, which is consist with experimental results. It suggests that applying CuOx/spiro-OMeTAD bilayer is an efficient way to improve performance of perovskite solar cell.

Among many photovoltaic conversion technologies, perovskite solar cells have received significant research interests as effective photovoltaic materials owing to their high solar conversion efficiencies and low cost. However, the performance of perovskite solar cells is limited by the instability of CH3NH3PbI3 to water and ambient moisture. To address this issue, in this study, we introduced a new fundamental approach that utilizes 4-tert-butylpyridine (tBP) as the surface modification agent to enhance the performance and stability of CH3NH3PbI3-based perovskite solar cells fabricated in ambient air. The tertiary butyl group in tBP is highly hydrophobic, leading to the formation a hydrophobic layer on the surface of CH3NH3PbI3, thus increasing the moisture stability of perovskite solar cells. With this strategy, the performance of perovskite solar cells prepared at even >50% RH in ambient air was tremendously enhanced by as much as 200% compared to that without tBP additive. Besides, the stability of pero...

The numerical simulation tool SCAPS-1D was used to analyze perovskite solar cell having the architecture ITO/ PEDOT:PSS or GO /CH3NH3PbI3-xClx/ PCBM /Au contains inverted planar hetero-junction device. In this work, we investigated the effect of inserting the Graphene Oxide (GO) as Hole Transport layer (HTL) on the performance of perovskite solar cells. Simulation results show that the use of GO as a hole transport layer is efficient. The efficiency of PSCs based on GO HTL was increased by about 1.6 % compared to the conventional PEDOT:PSS HTL device. The obtained results of optimizing the thickness of GO HTL exhibited an optimum value around 10 nm with an efficiency of 12.35 %, Voc of 1.19 V and FF of 54.8 %. We have also shown that the performance of device for high GO carrier density is a better than with low ones. In addition, increasing the temperature beyond the optimum value obtained around 320 K for both HTL materials (GO and PEDOT:PSS) has detrimental effect on the performance of the perovskite solar cells however the device is more sensitive to the temperature with PEDOT:PSS than the GO ones. The effect of band gap of GO on the performance of device is also studied. The obtained results underline the determining role playedby this parameter with an optimum value around 3.25 eV.

Parasitic optical losses, including free-carrier absorption and absorption from the rear mirror, could significantly affect the performance of solar cells. Although estimates of their influence have been made in the past, they have not previously been incorporated into the absorptivity of semiconductor materials and their influence on the performance of perovskite solar cells studied quantitatively. This paper numerically investigates the impact of both typical kinds of parasitic optical losses on the performance of perovskite solar cells utilizing the detailed balance model. It is found that the free carrier absorption loss has nearly no influence on the performance of perovskite solar cells, but parasitic absorption at the rear mirror can significantly affect the performance of solar cells. For thin film perovskite solar cells, parasitic absorption significantly affects the short circuit current, open circuit voltage and power conversion efficiency (PCE), but for thick solar cells, the short circuit current is nearly independent of the parasitic absorption; it seriously affects the open circuit voltage and PCE.

In recent years, perovskite solar cells have obtained a rapid development due to their large light absorption coefficient, low-cost and high power conversion efficiency (PCE). In this study, the one-dimensional ordered ZnO nanorod arrays were prepared on FTO glasses by chemical bath deposition at low temperature. TiO2 nanoparticles from different kinds of solution were further spin-coated onto the ZnO nano arrays to form ZnO/TiO2 composite nano arrays, as the electron transfer layer in perovskite solar cells. The microstructure of different ZnO/TiO2 composite nano arrays and their corresponding photovoltaic performance of the solar cells were investigated. It was found that the cells based on ZnO nano arrays treated by TiO2 nanoparticle paste exhibit the highest PCE. The influence of TiO2 paste concentration on the photovoltaic performance of cells was further investigated. It indicated that the cell achieves best photovoltaic performance at TiO2 paste concentration of 0.1 mol/L: open circuit voltage ( V oc) of 0.93 V, short circuit current ( J sc) of 15.30 mA cm−2, filling factor ( FF ) of 43% and PCE of 6.07%. The treatment of TiO2 paste on ZnO nano arrays results in perovskite nanoparticles can effectively fill into the cracks between ZnO nanorods and a flat and compact perovskite layer can also form on the top of ZnO nano arrays. These effectively enhance the loading of perovskite and suppress the recombination between carriers in cells, resulting in an improved photovoltaic performance. A further treatment of ZnO/TiO2 paste arrays with TiCl4 aqueous solution can significantly improve the photovoltaic performance of the perovskite solar cells: V oc=0.99 V, J sc=19.09 mA cm−2, FF =58%, and PCE of 11%. The TiCl4 treatment of ZnO/TiO2 composite arrays introduces small TiO2 nanoparticles (~3 nm) into nano arrays. The small nanoparticles can fully fill the cracks between the nanorods and create better contact between perovskite (both in top layer and the arrays) and nano arrays. The photo induced carrers can rapidly transfer via ZnO nanorods to the conductive substrates. Furthermore, the introduce of small TiO2 nanoparticles also increases the surface area of electrode to absorb more perovskite, and hence improve the adsorption of light and result in an improved photovoltaic performance of the cells.

Enhanced performance of CsPbBr3 perovskite solar cells by reducing the conduction band offsets via a Sr-modified TiO2 layer

Design and simulation of efficient tin based perovskite solar cells through optimization of selective layers: Theoretical insights

For the perovskite solar cells (PSCs), the performance of the PSCs has become the focus of the research by improving the quality of the perovskite absorption layer. So far, the performance of the large-area PSCs is lower than that of small-area PSCs. In the paper, the experiments were designed to improve the photovoltaic performance of the large-area PSCs by improved processing technique. Here we investigated the optoelectronic properties of the prototypical CH3NH3PbI3(MAPbI3) further modulated by introducing other extrinsic ions (specifically codoped Cl−and 5-AVA+). Moreover, we used inorganic electron extraction layer to achieve very rapid photogenerated carrier extraction eliminating local structural defects over large areas. Ultimately, we fabricated a best-performing perovskite solar cell based on codoping Cl anion and 5-AVA cation which uses a double layer of mesoporous TiO2and ZrO2as a scaffold infiltrated with perovskite and does not require a hole-conducting layer. The experiment results indicated that an average efficiency of double-mesoporous layer-based devices with codoping Cl anion and 5-AVA cation was obtained with exceeding 50% enhancement, compared to that of pure single-mesoporous layer-based device.

Solar cells based on hybrid organic-inorganic perovskite materials, with fascinating properties like broad optical absorption spectrum, low exciton binding energy, long charge diffusion length, and high charge mobility, have emerged as one of the promising candidates for third generation photovoltaics. Till date, power conversion efficiency (PCE) achieved in these solar cells is more than 22% by employing low-cost production techniques. The performance of high-efficiency perovskite solar cells is extremely dependent on the quality of the absorber perovskite layer like grain size, roughness and presence of defects. Here, we have done a comparative study of the performance of mixed halide CH3NH3PbIxCl3-x, single halide CH3NH3PbI3 and bulk heterojunction CH3NH3PbI3-PC71BM (BHJ) perovskite solar cells (PSCs) with p-i-n architecture. The morphology of the different perovskite layers is analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to understand its influence on the device performance. Defects density of states (DOS) arising from morphological variations can critically influence the overall performance of the perovskite solar cells. The PCE of the mixed and single halide, and bulk heterojunction perovskite solar cells is correlated with the defect density of states studied by means of capacitance spectroscopy.

Predicting the device performance of the perovskite solar cells from the experimental parameters through machine learning of existing experimental results