Designing functional fullerenes with roles beyond defect passivation and electron‐transporting for perovskite solar cells (PSCs) is essential to the development of fullerenes and PSCs. Here, the authors design and synthesize a functional fullerene, FPD, composed of a C60 cage, a porphyrin ring, and three pentafluorophenyl groups. The structure features of FPD enable it can form chemical interactions with the perovskite lattices. These interactions enhance the defect passivation effect and prevent the decomposition of perovskite under irradiation. As a result, the FPD‐based device yields an improved power conversion efficiency of 23% with substantially enhanced operational stability (T80 > 1500 h). Furthermore, once got damaged, the FPD can prevent lead leakage by forming a stable and water‐insoluble complex (FPD‐Pb). Their findings provide a novel strategy to achieve high‐performance and eco‐friendly PSCs with functional fullerene materials.
Preparation of phase-pure and stable formamidinium-based lead iodide (FAPbI3) perovskites is essential for fabricating high-performance perovskite solar cells (PSCs). Here, we report using very little CsPbBr3 perovskite (2%, molar ratio...
Carrier recombination at the buried SnO 2 /perovskite interface limits the efficiency and stability of n-i-p-structured perovskite solar cells (PSCs). Herein, we report an In 2 O 3 interfacial layer with the distinctive structure of the monolithic compact/nanostructured bilayer. The partial hydrolysis nature of the In 3+ ion enables the formation of nanorods on top of the compact In 2 O 3 layer when spin-coating the In(NO 3 ) 3 aqueous solution. This novel interfacial layer reduces the pinholes of the SnO 2 film and increases the contact area between the perovskite and electron transport material.
Tin oxide (SnO2) is widely used as an electron transport layer (ETL) to fabricate planar perovskite solar cells (PSCs) due to their easy and low‐temperature processed fabrication. Enhancing carrier extraction and energy level alignment at the perovskite/SnO2 interface is vital to improve the device performance further. Here, we demonstrate a double‐layered SnO2/ NH4Cl‐SnO2 as an efficient ETL. The top NH4Cl‐SnO2 shows a better energy level alignment with the perovskite and reduced alkalinity to avoid perovskite degradation, resulting in enhanced electron extraction efficiency and interfacial stability. Furthermore, the bottom SnO2 retains the capability of efficient carrier transport to avoid charge accumulation. As a result, we achieve a champion device with a power conversion efficiency of 21.01% and negligible hysteresis. Moreover, the corresponding PSCs show much improved operational stability, retaining 80% of the initial efficiency after 1090 hours of operation at the maximum power point under 1‐sun illumination. While the pristine SnO2 based PSCs only insist on 278 hours before losing 20% of the initial efficiency.
Constructing 2D/3D perovskite heterojunctions is effective for the surface passivation of perovskite solar cells (PSCs). However, previous reports that studying perovskite post-treatment only physically deposits 2D perovskite on the 3D perovskite, and the bulk 3D perovskite remains defective. Herein, we propose Cl2-dissolved chloroform as a multifunctional solvent for concurrently constructing 2D/3D perovskite heterojunction and inducing the secondary growth of the bulk grains. The mechanism of how Cl2 affects the performance of PSCs is clarified. Specifically, the dissolved Cl2 reacts with the 3D perovskite, leading to Cl/I ionic exchange and Ostwald ripening of the bulk grains. The generated Cl− further diffuses to passivate the bulk crystal and buried interface of PSCs. Hexylammonium bromide dissolved in the solvent reacts with the residual PbI2 to form 2D/3D heterojunctions on the surface. As a result, we achieved high-performance PSCs with a champion efficiency of 24.21% and substantially improved thermal, ambient, and operational stability.
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