Recent Research Developments of Perovskite Solar Cells

Improvement Strategies for Stability and Efficiency of Perovskite Solar Cells

Recently, perovskites have garnered great attention owing to their outstanding characteristics, such as tunable bandgap, rapid absorption reaction, low cost and solution-based processing, leading to the development of high-quality and low-cost photovoltaic devices. However, the key challenges, such as stability, large-area processing, and toxicity, hinder the commercialization of perovskite solar cells (PSCs). In recent years, several studies have been carried out to overcome these issues and realize the commercialization of PSCs. Herein, the stability and photovoltaic efficiency improvement strategies of perovskite solar cells are briefly summarized from several directions, such as precursor doping, selection of hole/electron transport layer, tandem solar cell structure, and graphene-based PSCs. According to reference and analysis, we present our perspective on the future research directions and challenges of PSCs.

Efficiency improvement of inverted perovskite solar cells enabled by PTAA/MoS2double hole transporters

Hole transport layer (HTL) plays a critical role in perovskite solar cells (PSCs). We focus on the improvement of PSCs performance with MoS₂nanosheets as the anode buffer layer in the inverted photovoltaic structure. PSC with single MoS₂buffer layer shows poor performance in power conversion efficiency (PCE) and the long-term stability. By combination of MoS₂and Poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) as double-layer HTL, the PCE is improved to 18.47%, while the control device with PTAA alone shows a PCE of 14.48%. The same phenomenon is also found in 2D PSCs. For double-layer HTL devices, the PCE reaches 13.19%, and the corresponding PCE of the control group using PTAA alone is 10.13%. This significant improvement is attributed to the reduced interface resistance and improved hole extraction ability as shown by the electric impedance spectroscopy and fluorescence spectroscopy. In addition, the improved device exhibits better stability because the PCE still maintains 66% of the initial value after 500 h of storage, which is higher than the 47% of the remaining PCE from device based on single PTAA or MoS₂. Our results demonstrate the potential of polymer/inorganic nanomaterial as a double-layer buffer material for PSCs.

Major Impediment to Highly Efficient, Stable and Low-Cost Perovskite Solar Cells

Organic–inorganic hybrid perovskite solar cells (PSCs) have made immense progress in recent years, owing to outstanding optoelectronic properties of perovskite materials, such as high extinction coefficient, carrier mobility, and low exciton binding energy. Since the first appearance in 2009, the efficiency of PSCs has reached 23.3%. This has made them the most promising rival to silicon-based solar cells. However, there are still several issues to resolve to promote PSCs’ outdoor applications. In this review, three crucial aspects of PSCs, including high efficiency, environmental stability, and low-cost of PSCs, are described in detail. Recent in-depth studies on different aspects are also discussed for better understanding of these issues and possible solutions.

Organic Charge Carriers for Perovskite Solar Cells

The photovoltaic field is currently experiencing the "perovskite revolution". These materials have been known for decades, but only recently have they been applied in solid-state solar cells to obtain outstanding power conversion efficiencies. Given that the variety of perovskites used so far is limited, a lot of attention has been devoted to the development of suitable organic charge-transport materials to improve device performance. In this article, we will focus on the most promising materials able to transport electrons or holes from a structural point of view. Thereby, we focus on organic materials owing to their ease of preparation and manipulation, and this is nicely combined with the potential tuning of their properties through chemical synthesis.

Morphology control of the perovskite films for efficient solar cells

In the past two years, the power conversion efficiency (PCE) of organic–inorganic hybrid perovskite solar cells has significantly increased up to 20.1%.