Improving Interfacial Charge Recombination in Planar Heterojunction Perovskite Photovoltaics with Small Molecule as Electron Transport Layer

Abstract

Although perovskite solar cells (PSCs) have emerged as a promising alternative to widely used fossil fuels, the involved high‐temperature preparation of metal oxides as a charge transport layer in most state‐of‐the‐art PSCs has been becoming a big stumbling block for future low‐temperature and large‐scale R2R manufacturing process. Such an issue strongly encourages scientists to find new type of materials to replace metal oxides. Except for expensive PC61BM with unmanageable morphology and electrical properties, the past investigation on the development of low‐temperature‐processed and highly efficient electron transport layers (ETLs) has met some mixed success. In order to further enhance the performance of all‐solution‐processed PSCs, we propose a novel n‐type sulfur‐containing small molecule hexaazatrinaphtho[2,3‐c][1,2,5]thiadiazole (HATNT) with high electron mobility up to 1.73 × 10−2 cm2 V−1 s−1 as an ETL in planar heterojunction PSCs. A high power conversion efficiency of 18.1% is achieved, which is fully comparable with the efficiency from the control device fabricated with PC61BM as ETL. This superior performance mainly attributes from more effective suppression of charge recombination at the perovskite/HATNT interface than that between the perovskite and PC61 BM. Moreover, high electron mobility and strong interfacial interaction via SI or SPb bonding should be also positive factors. Significantly, our results undoubtedly enable new guidelines in exploring n‐type organic small molecules for high‐performance PSCs.

Recent Progress in Organic Electron Transport Materials in Inverted Perovskite Solar Cells

“…After recognizing the importance of sulfur–Pb interaction as well as sulfur's passivation of surface trap of perovskite layer, another new azaacene‐based derivative (HATNT) with the mobility of 1.73 × 10 −2 cm V −1 s −1 has been synthesized. Due to well‐matched LUMO and HOMO with conduction band and valence band of the perovskite layer, respectively, the PCE of the devices based on HATNT as ETL has reached 18.2% without hysteresis . Continuing on this research, another new azaacene‐based derivative (TDTP) was designed, synthesized and implemented as an ETL in PSCs by our group.…”

Lead‐Free Double Perovskite Cs2SnX6: Facile Solution Synthesis and Excellent Stability

“…Organic-inorganic lead halide perovskites have recently been intensively investigated due to their superior optoelectronic and photovoltaic characteristics. Since their pioneering application in solar cells with an efficiency of 3.8% in 2009, [1,2] researchers have made great efforts to further develop metal halide perovskites in various applications such as fieldeffect transistors, [3] solar cells, [4][5][6][7][8] photodetectors, [9] thermoelectrics, [10] tandem devices, [11] light-emitting electrochemical cells, [12] diodes, [13,14] and laser. [15,16] Despite the rapid growth of the organic-inorganic lead halide perovskite research efforts in both academia and industry, two biggest challenges still remain and hinder their widespread applications.…”

Compositional and Solvent Engineering in Dion–Jacobson 2D Perovskites Boosts Solar Cell Efficiency and Stability

“…[16,17,[21][22][23][24][25] The long-term stability of 3D halide perovskites with organic cations is still an open issue and under intense investigation. [16,17,[21][22][23][24][25] The long-term stability of 3D halide perovskites with organic cations is still an open issue and under intense investigation.…”