Perovskite Solar Cells In Future Research Articles

Low lead inorganic Zn-based mixed-halide perovskites CsPb0.625Zn0.375I3−β X β (X = Cl or Br) for energy generation with 23.5% efficiency

Hybrid perovskite (HP) solar cells have garnered significant attention in recent years for their excellent light absorption, long carrier lifetime, and high diffusion length, resulting in high power conversion efficiency and superior optical performance compared to silicon solar cells. However, the organic component in HP solar cells is vulnerable to thermal variations and the presence of lead (Pb) poses a threat to the environment. To address these issues, this work proposes the use of all-inorganic halide perovskite (IHP) materials with low lead content as the absorber layer in four different perovskite solar cell configurations: CsPb0.625Zn0.375I2Br, CsPb0.625Zn0.375IBr2, CsPb0.625Zn0.375I2Cl, CsPb0.625Zn0.375ICl2. In addition, owing to the consideration novel IHP materials, it is important to identify the appropriate properties of transport layers since conventional transport layers are best suited to conventional organic–inorganic halide perovskites and may not work well with proposed IHP. Therefore, the appropriate electron transport layer (ETL) has also been investigated through optimization of electron affinity (4.0 eV − 4.23 eV), mobility (0.004 cm2/Vs to 4 cm2/Vs), and donor doping density (1015 cm−3 to 1018 cm−3). The device performance has been further analysed and optimized by varying the active layer thickness. The selected ETL is then combined with the absorber layers to evaluate performance. The effect of varying the thickness of the absorption layer is observed in all four device arrangements. Simulation results show that CsPb0.625Zn0.375ICl2 performed best among the mentioned absorber materials, with a power conversion efficiency of 23.5% with ETL parameters of 4.00 eV (electron affinity, χ), 4 cm2/Vs (electron mobility, μ n), 1×1018 cm−3 (donor doping density, Nd) and absorber layer thickness of 500 nm. Proposed work may open a window for the development of a new class of environment friendly and stable perovskite solar cells in future.

Enhanced Charge Extraction in Metal–Perovskite–Metal Back-Contact Solar Cell Structure Through Electrostatic Doping: A Numerical Study

In conventional perovskite solar cells (PSCs), a thin active layer of perovskite is sandwiched between two charge transport layers (CTLs)-electron transport layer (ETL) and hole transport layer (HTL). CTLs help in extracting and navigating the photogenerated electron-hole (e-h) pairs to the respective electrodes. Although this phenomenon gives high-energy conversion efficiencies but leads to quite a few performances as well as fabrication challenges. The ways to partially overcome these challenges are to have a device without the need of having CTLs altogether and opting for the back-contact (BC) design for PSCs. Dipole fields (DFs) present at the metal perovskite interface may be thought for their possible utilization to have CTL-free BC PSC. However, the performance of such devices is limited by the difference between the metal work functions across the perovskite layer. In this article, we report the results for our studies to establish that an electrostatically doped DF-assisted metal perovskite metal back-contact (ED-DF-MPM) PSC structure has the ability to overcome the limitations of DF-assisted metal perovskite metal back-contact (DF-MPM) PSCs. As a part of the work carried out here, ED p-n-junction and corresponding built-in potential have been combined for DF-assisted extraction of generated carriers within the perovskite layer so as to enhance the collection probability and open-circuit voltage. Quantitively, 32.7%, 10.6%, and 8.6% improvement in short-circuit current density (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> ), open-circuit voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> ), and fill factor (FF) are obtained, respectively, which resulted in an observation of 59.4% improvement in power conversion efficiency (PCE) for ED-DF-MPM PSC compared to DF-MPM PSC. Besides that, the reported ED-DF-MPM PSC structure delivers the photovoltage and photocurrent of 659 mV and 14.19 mA ·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , respectively. The work reported in this article may pave the way for the development of “transport layer-free” ED scalable and low-cost PSCs in future.

Hollow TiO2 spheres as mesoporous layer for better efficiency and stability of perovskite solar cells

Hollow TiO2 spheres were synthesized by template method, with the diameters was 200 nm and the thickness of shell about 30 nm. The high-quality perovskite films fabricated on the hollow TiO2 mesoporous layer demonstrate smooth surface and large grain size, resulting in the better scattering light ability and fewer defects. The efficiency of the perovskite solar cells prepared on hollow mesoporous layer can reach 17.60%, which is an approximately 14% higher than the PCE of conventional mesoporous layer devices under the same condition. Importantly, the solar cells with hollow TiO2 can exhibit better stability than the cells with mesoporous TiO2 after aging 30 days in 65% relative humidity under dark conditions. The results indicate that the hollow TiO2 mesoporous layer will be a candidate for better efficient and stable CH3NH3PbI3 perovskite solar cells, and this structure provides a direction for the design of novel mesoporous layers for perovskite solar cells in future.

Room-Temperature Sputtered SnO2 as Robust Electron Transport Layer for Air-Stable and Efficient Perovskite Solar Cells on Rigid and Flexible Substrates

Extraordinary photovoltaic performance and intriguing optoelectronic properties of perovskite solar cells (PSCs) have aroused enormous interest from both academic research and photovoltaic (PV) industry. In order to bring PSC technology from laboratory to market, material stability, device flexibility, and scalability are important issues to address for vast production. Nevertheless, PSCs are still primarily prepared by solution methods which limit film scalability, while high-temperature processing of metal oxide electron transport layer (ETL) makes PSCs costly and incompatible with flexible substrates. Here, we demonstrate rarely-reported room-temperature radio frequency (RF) sputtered SnO2 as a promising ETL with suitable band structure, high transmittance, and excellent stability to replace its solution-processed counterpart. Power conversion efficiencies (PCEs) of 12.82% and 5.88% have been achieved on rigid glass substrate and flexible PEN substrate respectively. The former device retained 93% of its initial PCE after 192-hour exposure in dry air while the latter device maintained over 90% of its initial PCE after 100 consecutive bending cycles. The result is a solid stepping stone toward future PSC all-vapor-deposition fabrication which is being widely used in the PV industry now.

Boron and phosphorus co-doped carbon counter electrode for efficient hole-conductor-free perovskite solar cell

Chemical doping is adopted to tune the work function and electrical conductivity of carbon counter electrode (CE) in HTM-free organometallic halide perovskite solar cells (PSCs). In this work, the boron and phosphorus co-doped carbon (BPC) CE is constructed by coating a B doped carbon layer onto the P-doped carbon (PC). The work function of BPC CE with B/P co-doping (B: 2.68at.%, P: 2.23at.%) is thus regulated to 5.12eV from the 5.01eV of pure carbon and 4.81eV of PC, and the sheet resistance is modulated to 8.41Ωsq−1 from 14.75Ωsq−1 of pure carbon and 7.89Ωsq−1 of PC. As a consequence, the BPC-based PSCs deliver a power conversion efficiency of 6.78%, higher than those of pristine carbon (3.72%), PC (5.39%) and BC (5.20%) based PSCs, and even comparable to that of conventional Au-based device (7.22%), due to the enhanced hole extraction ability and the maintained high electronic conductivity. Moreover, the good stability in ambient condition over a period of 720h is also demonstrated in the BPC-based PSCs. The successful application of BPC CE in PSCs shows a promising way for fabricating low-cost, large-scale and highly efficient PSCs in future.

Mapping the Photoresponse of CH3NH3PbI3 Hybrid Perovskite Thin Films at the Nanoscale.

Perovskite solar cells (PSCs) based on thin films of organolead trihalide perovskites (OTPs) hold unprecedented promise for low-cost, high-efficiency photovoltaics (PVs) of the future. While PV performance parameters of PSCs, such as short circuit current, open circuit voltage, and maximum power, are always measured at the macroscopic scale, it is necessary to probe such photoresponses at the nanoscale to gain key insights into the fundamental PV mechanisms and their localized dependence on the OTP thin-film microstructure. Here we use photoconductive atomic force microscopy spectroscopy to map for the first time variations of PV performance at the nanoscale for planar PSCs based on hole-transport-layer free methylammonium lead triiodide (CH3NH3PbI3 or MAPbI3) thin films. These results reveal substantial variations in the photoresponse that correlate with thin-film microstructural features such as intragrain planar defects, grains, grain boundaries, and notably also grain-aggregates. The insights gained into such microstructure-localized PV mechanisms are essential for guiding microstructural tailoring of OTP films for improved PV performance in future PSCs.

Towards toxicity removal in lead based perovskite solar cells by compositional gradient using manganese chloride

We report synthetic steps towards a lead free manganese based perovskite MAPbxMn1–xI1+2xCl2–2x. Fabrication of a cell with an inverted planar architecture at low processing temperatures shows its potential application in future perovskite solar cells.