PbI₂/CH₃NH₃Cl Mixed Precursor–Induced Micrometer‐Scale Grain Perovskite Film and Room‐Temperature Film Encapsulation toward High Efficiency and Stability of Planar Perovskite Solar Cells

Abstract

transparent conductive substrate, an electron transport layer, a perovskite layer, a hole transport layer, and a metal electrode. Among these parts, the perovskite layer plays a vital role in determining the device performance since it closely relates to light absorption and photocarrier transport. The quality of the perovskite film can be assessed in terms of morphology and electronic properties. A dense perovskite film without pinholes would reduce the shunting paths and carrier recombination between electron selective layer and hole transport layer, while the smooth surface with low roughness facilitates a conformal and full coverage coating of the carrier selective layer to avoid direct contact between perovskite and metal electrode. [17,18] Perovskite film with a small defect density can suppress the ion diffusion and charging effect, which have been considered as the major cause of the hysteretic behavior in perovskite-based photovoltaic devices. [19,20] According to the fabrication process, the perovskite film can be obtained through a one-step method or sequential deposition. [9,12] As for the one-step method, stoichiometric precursors are mixed in a solvent and transformed into perovskite film after solvent evaporation and post-treatment, which stands for the simplest processing. In spite of advantages in cost and upscaling fabrication, crystal growth in the onestep method is relatively hard to control, and the crystallization process is sensitive to the atmosphere condition. Alternatively, the perovskite thin film can also be prepared through sequential deposition, a process with easily controlled nucleus formation and crystal growth. [21,22] However, the PCE of the device based on sequential deposition processed perovskite thin film still lags behind and needs further improvement.The stability of perovskite solar cell is another key issue which is closely related to its practical application. The current organic-inorganic halide perovskite solar cells typically show poor stability in ambient environment, where the moisture is regarded as the main cause of performance deterioration. [23][24][25][26] Compared to the constant pursuit of PCE, less efforts have been paid on the understanding of degradation mechanism and enhancement of device stability. Various strategies have been demonstrated to improve the tolerance to moisture or The power conversion efficiency and the stability are the most important figures of merit for perovskite solar cells which attract increasing attention in recent years. Herein, the growth of high-quality perovskite films with micrometer-scale grain size through sequential deposition is first reported using PbI 2 /CH 3 NH 3 Cl mixed precursors during the first step of deposition. The amount of CH 3 NH 3 Cl in the precursor has a great influence on the morphology of perovskite films and the device performance. Compared with traditional sequential deposition with pure PbI 2 in the first step, this method renders the perovskite solar cells with an improved power conversion efficienc...

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

“…2 Graphite-and carbon black-based back electrodes Generally speaking, a PSC is based on a perovskite layer 48,49 sandwiched between an ETM and a HTM. 50,51 The ETM usually consists of TiO 2 or another n-type semiconductor anode, [52][53][54] while the back electrode is deposited on top of the HTM.…”

Groups-dependent phosphines as the organic redox for point defects elimination in hybrid perovskite solar cells

“…Hybrid perovskite are susceptible to various degradation factors, including moisture, oxygen, heat, electric field, and ultraviolet exposure [11][12][13][14], which are the main causes of instable photovoltaic conversion for PSCs [15]. Many researches have exhibit effective elimination of external factors by encapsulation [16][17][18][19] and interface modification [20], which has improved the stability of the device. However, even if the interface is well modified to block the corrosion of water and oxygen in the external environment, internal degradation stress such as electrical and thermal stress cannot be eliminated, which leads to decomposition of the perovskite [21].…”

Encapsulation and Stability Testing of Perovskite Solar Cells for Real Life Applications

“…ALD deposited films can also be combined with other films to form a barrier multilayer for enhanced encapsulation properties. , For example, combining the ALD coated alumina film with a hydrophobic surface modification with 1 H ,1 H ,2 H ,2 H -perfluorodecyltrichlorosilane has also been shown to enhance the barrier performance against moisture ingress . In addition to ALD, e-beam evaporation , and RF sputtering have been used for depositing protective inorganic thin films, while plasma enhanced chemical vapor deposition (PECVD) has been used for depositing CF film encapsulation . Air brush coating of hydrophobic zirconia films (several microns thick) was also reported …”