Under the spotlight: The organic–inorganic hybrid halide perovskite for optoelectronic applications

A Review of Perovskites Solar Cell Stability

Perovskite solar cells (PSCs) have developed rapidly over the past few years, and the power conversion efficiency of PSCs has exceeded 20%. Such high performance can be attributed to the unique properties of perovskite materials, such as high absorption over the visible range and long diffusion length. Due to the different diffusion lengths of holes and electrons, electron transporting materials (ETMs) used in PSCs play a critical role in PSCs performance. As an alternative to TiO2 ETM, ZnO materials have similar physical properties to TiO2 but with much higher electron mobility. In addition, there are many simple and facile methods to fabricate ZnO nanomaterials with low cost and energy consumption. This review focuses on recent developments in the use of ZnO ETM for PSCs. The fabrication methods of ZnO materials are briefly introduced. The influence of different ZnO ETMs on performance of PSCs is then reviewed. The limitations of ZnO ETM-based PSCs and some solutions to these challenges are also discussed. The review provides a systematic and comprehensive understanding of the influence of different ZnO ETMs on PSCs performance and potentially motivates further development of PSCs by extending the knowledge of ZnO-based PSCs to TiO2 -based PSCs.

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Perovskite Solar Cells with ZnO Electron-Transporting Materials

High-efficiency and low-cost perovskite solar cells (PVKSCs) are an ideal candidate for addressing the scalability challenge of solar-based renewable energy. The dynamically evolving research field of PVKSCs has made immense progress in solving inherent challenges and capitalizing on their unique structure-property-processing-performance traits. This review offers a unique outlook on the paths toward commercialization of PVKSCs from the interfacial engineering perspective, relevant to both specialists and nonspecialists in the field through a brief introduction of the background of the field, current state-of-the-art evolution, and future research prospects. The multifaceted role of interfaces in facilitating PVKSC development is explained. Beneficial impacts of diverse charge-transporting materials and interfacial modifications are summarized. In addition, the role of interfaces in improving efficiency and stability for all emerging areas of PVKSC design are also evaluated. The authors' integral contributions in this area are highlighted on all fronts. Finally, future research opportunities for interfacial material development and applications along with scalability-durability-sustainability considerations pivotal for facilitating laboratory to industry translation are presented.

Toward Perovskite Solar Cell Commercialization: A Perspective and Research Roadmap Based on Interfacial Engineering.

We report a dopant-free polymeric hole transport material (HTM) that is based on benzo[1,2-b:4,5:b′]dithiophene and 2,1,3-benzothiadiazole, which results in highly efficient and stable perovskite solar cells (∼17.3% for over 1400 h at 75% humidity). The HTM comprises a random copolymer (RCP), which is characterized using UV-vis absorption spectroscopy, cyclic voltammetry, space-charge-limited current, and grazing-incidence wide-angle X-ray scattering. The RCP-based perovskite solar cell exhibits the highest efficiency (17.3%) in the absence of dopants [lithium bis(trifluoromethanesulfonyl)imide and tert-butylpyridine]. The observed efficiency is attributed to a deep HOMO energy level and high hole mobility. In addition, the long-term stability of the device is dramatically improved by avoiding deliquescent or hygroscopic dopants and by introducing a hydrophobic polymer layer. RCP devices maintain their initial efficiency for over 1400 h at 75% humidity, whereas devices made of HTMs with additives fail after 900 h.

Dopant-free polymeric hole transport materials for highly efficient and stable perovskite solar cells

Suitable electrode interfacial layers are essential to the high performance of perovskite planar heterojunction solar cells. In this letter, we report magnetron sputtered zinc oxide (ZnO) film as the cathode interlayer for methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell. Scanning electron microscopy and X-ray diffraction analysis demonstrate that the sputtered ZnO films consist of c-axis aligned nanorods. The solar cells based on this ZnO cathode interlayer showed high short circuit current and power conversion efficiency. Besides, the performance of the device is insensitive to the thickness of ZnO cathode interlayer. Considering the high reliability and maturity of sputtering technique both in lab and industry, we believe that the sputtered ZnO films are promising cathode interlayers for perovskite solar cells, especially in large-scale production.

Magnetron sputtered zinc oxide nanorods as thickness-insensitive cathode interlayer for perovskite planar-heterojunction solar cells

Although organic small molecule spiro-OMeTAD is widely used as a hole-transport material in perovskite solar cells, its limited electric conductivity poses a bottleneck in the efficiency improvement of perovskite solar cells. Here, a low-cost and easy-fabrication technique is developed to enhance the conductivity and hole-extraction ability of spiro-OMeTAD by doping it with commercially available benzoyl peroxide (BPO). The experimental results show that the conductivity increases several orders of magnitude, from 6.2×10−6 S cm−1 for the pristine spiro-OMeTAD to 1.1×10−3 S cm−1 at 5 % BPO doping and to 2.4×10−2 S cm−1 at 15 % BPO doping, which considerably outperform the conductivity of 4.62×10−4 S cm−1 for the currently used oxygen-doped spiro-OMeTAD. The fluorescence spectra suggest that the BPO-doped spiro-OMeTAD–OMeTAD layer is able to efficiently extract holes from CH3NH3PbI3 and thus greatly enhances the charge transfer. The BPO-doped spiro-OMeTAD is used in the fabrication of perovskite solar cells, which exhibit enhancement in the power conversion efficiency.

Benzoyl Peroxide as an Efficient Dopant for Spiro-OMeTAD in Perovskite Solar Cells.

The invention discloses a perovskite solar cell preparation method based on the full-coating process, and relates to solar cells. The perovskite solar cell preparation method based on the full-coating process is low in cost, high in efficiency and industrialized. The method comprises the steps that (1) an electron transfer layer, a perovskite active layer and a hole transfer layer are sequentially prepared on a transparent conductive substrate by the adoption of the coating process, and slot-die coating or spraying-type coating is adopted in the coating process; (2) the hole transfer layer is coated with a top electrode, and screen printing and knife coating are adopted for coating. The problem of the process and cost of evaporation and precious metal electrode printing are solved, and the problem that the perovskite layer may be damaged by high-temperature carbon paste is solved. The one-step annealing method is adopted, in other words, annealing is carried out at the temperature ranging from 70 DEG C to 150 DEG C after coating is carried out on all the functional layers. The manufacturing technology is further simplified, and the device performance and stability can be effectively improved.

Perovskite solar cell preparation method based on full-coating process

The invention provides roll-to-roll production equipment and method for a perovskite thin film solar cell assembly, and relates to solar cells. The production equipment is provided with a first roll and a second roll. A first module, a second module and a third module are arranged between the first roll and the second roll. The first roll is an unwinding roll and is used for assembling base material rolls without coatings. The first module is located between the first roll and the second module and is used for manufacturing and structuralizing transparent conducting electrodes. The second module is located between the first module and the third module and is used for manufacturing and structuralizing perovskite active layers. The third module is located between the second module and the second roll and is used for manufacturing and structuralizing electrodes. The second roll is a winding roll and is used for winding manufactured perovskite thin film solar cells. The production method includes the steps of manufacturing and/or structuralizing of the transparent conducting electrodes, manufacturing and/or structuralizing of the perovskite active layers and manufacturing and/or structuralizing of the electrodes. By means of the roll-to-roll production equipment and method, the performance and production efficiency of the perovskite thin film solar cell can be improved, and the cost can be reduced.

Roll-to-roll production equipment and method for perovskite thin film solar cell assembly

The invention provides a perovskite type solar cell with sputtering ZnO as an electron transfer layer and preparation and relates to solar cells The perovskite type solar cell is provided with a transparent conducting glass substrate, the ZnO electron transfer layer, a perovskite type material layer, a hole transfer layer and a metal back electrode layer from bottom to top in sequence The preparation comprises the steps that the transparent conducting glass substrate is preprocessed, a ZnO thin film is prepared on the transparent conducting glass substrate, and heating and annealing are conducted, in other words, the ZnO electron transfer layer is sputtered; a DMF solution of PbI2 is prepared, the ZnO electron transfer layer is coated with the DMF solution of the PbI2 in a spinning mode to prepare a PbI2 thin film, the PbI2 thin film is then steeped into an isopropanol solution of CH3NH3I, and thus the perovskite type material layer is obtained; 2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, an acetonitrile solution of lithium bis(trifluoromethanesulphonyl)imide and 4-tert-butylpyridine are dissolved in a chlorobenzene solution, the perovskite type material layer is then coated with the solution in a spinning mode, the hole transfer layer is obtained, then the metal back electrode layer is obtained, and the perovskite type solar cell is obtained

Wang Baozeng

Papers

Magnetron sputtered zinc oxide nanorods as thickness-insensitive cathode interlayer for perovskite planar-heterojunction solar cells

Benzoyl Peroxide as an Efficient Dopant for Spiro-OMeTAD in Perovskite Solar Cells.

Perovskite solar cell preparation method based on full-coating process

Roll-to-roll production equipment and method for perovskite thin film solar cell assembly

Perovskite type solar cell with sputtering ZnO as electron transfer layer and preparation