Quantum Dot Interface-Mediated CsPbIBr2 Film Growth and Passivation for Efficient Carbon-Based Solar Cells

Limitations and Progresses in Carbon-Based Cesium Lead Halide Perovskite Solar Cells

Inorganic cesium lead halide perovskites (CsPbIxBr3-x, 0≤x≤3) are promising alternatives with great thermal stability. Additionally, the choice of moisture-resistive and dopant-free carbon as the electrode material can simultaneously solve the problems of stability and cost. Therefore, carbon electrode-based inorganic PSCs (C-IPSCs) represent a promising candidate for commercialization, yet both the efficiencies and stability of related devices demand further progress. This article reviews the recent advancement of C-IPSCs and then unravels the distinctive merits and limitations in this field. Subsequently, our perspective on various modification strategies is analyzed on a methodological level. Finally, this article outlooks the promising research contents and the remaining unresolved issues in this field. We believe that understanding and analyzing the related problems in this field are instructive to stimulate the future development of C-IPSCs.

SnS Quantum Dots Enhancing Carbon-Based Hole Transport Layer-Free Visible Photodetectors

The recombination of charges and thermal excitation of carriers at the interface between methylammonium lead iodide perovskite (PVK) and the carbon electrode are crucial factors that affect the optoelectronic performance of carbon-based hole transport layer (HTL)-free perovskite photodetectors. In this work, a method was employed to introduce SnS quantum dots (QDs) on the back surface of perovskite, which passivated the defect states on the back surface of perovskite and addressed the energy-level mismatch issue between perovskite and carbon electrode. Performance testing of the QDs and the photodetector revealed that SnS QDs possess energy-level structures that are well matched with perovskite and have high absorption coefficients. The incorporation of these QDs into the interface layer effectively suppresses the dark current of the photodetector and greatly enhances the utilization of incident light. The experimental results demonstrate that the introduction of SnS QDs reduces the dark current by an order of magnitude compared to the pristine device at 0 V bias and increases the responsivity by 10%. The optimized photodetector exhibits a wide spectral response range (350 nm to 750 nm), high responsivity (0.32 A/W at 500 nm), and high specific detectivity (>1 × 1012 Jones).

Functional Materials for Fabrication of Carbon-Based Perovskite Solar Cells: Ink Formulation and Its Effect on Solar Cell Performance

Perovskite solar cells (PSCs) have rapidly developed into one of the most attractive photovoltaic technologies, exceeding power conversion efficiencies of 25% and as the most promising technology to complement silicon-based solar cells. Among different types of PSCs, carbon-based, hole-conductor-free PSCs (C-PSCs), in particular, are seen as a viable candidate for commercialization due to the high stability, ease of fabrication, and low cost. This review examines strategies to increase charge separation, extraction, and transport properties in C-PSCs to improve the power conversion efficiency. These strategies include the use of new or modified electron transport materials, hole transport layers, and carbon electrodes. Additionally, the working principles of various printing techniques for the fabrication of C-PSCs are presented, as well as the most remarkable results obtained from each technique for small-scale devices. Finally, the manufacture of perovskite solar modules using scalable deposition techniques is discussed.

Seeding Agents in Metal Halide Perovskite Solar Cells: From Material to Mechanism

Metal halide perovskite solar cells (PSCs) have been showing up in the commercial field, with an inspiring power conversion efficiency (PCE) of over 26 % in the laboratory. The quality of perovskite films is still a bottleneck due to the random and fast crystallization of ionic perovskite materials. Seeding agent-mediated crystallization has consistently been recognized as an efficient method for preparing bulk single crystals and high-quality films. Herein, we summarized the seeding mechanism, characterization techniques, and seeding agents working in different locations during PSC device fabrication. This Review could further facilitate researchers with a deeper understanding of seeding agents and enhance more choices for seeding crystallization to improve the performance further and the device's large-scale fabrication toward commercialization.

Enhancing the Efficiency of Perovskite Solar Cells through Interface Engineering with MoS2 Quantum Dots

The interface of perovskite solar cells (PSCs) determines their power conversion efficiency (PCE). Here, the buried bottom surface of a perovskite film is efficiently passivated by using MoS₂ quantum dots. The perovskite films prepared on top of MoS₂-assisted substrates show enhanced crystallinity, as evidenced by improved photoluminescence and a prolonged emission lifetime. MoS₂ quantum dots with a large bandgap of 2.68 eV not only facilitate hole collection but also prevent the photogenerated electrons from flowing to the hole transport layer. Overall promotion leads to decreased trap density and an enhanced built-in electric field, thus increasing the device PCE from 17.87% to 19.95%.

Synergistic Effects of Bipolar Additives on Grain Boundary-Mediated Charge Transport for Efficient Carbon-Based Inorganic Perovskite Solar Cells

Carbon-based all-inorganic CsPbI_xBr_3-x perovskite solar cells offer high stability against heat and humidity and a suitable band gap for tandem and semitransparent photovoltaics. In CsPbI_xBr_3-x perovskite films, the defects at grain boundaries (GBs) cause charge trapping, reducing the efficiency of the cell. Electronic deactivation of GB has been a conventional strategy to suppress the trapping, but at the cost of charge carrier transport through the boundaries. Here, we turn the GBs into benign charge transport pathways with the aid of bipolar charge transport semiconductors, namely, Ti₃C₂T_X (MXene) and Spiro-OMeTAD, respectively. Thanks to the synergistic effects of both n- and p-type transport media, the charge transport is improved and balanced at the GBs. As a result, the cells achieve an efficiency of 12.7%, the highest among all low-temperature-processed carbon-based inorganic perovskite solar cells. Benign GBs also lead to enhanced light and aging stabilities. Our work demonstrates a proof-of-concept strategy of benign electronic modulation of GBs for solution-processed perovskite solar cells.