Carbon Nanoparticles in High‐Performance Perovskite Solar Cells

Abstract

Perovskite solar cells have attracted considerable interest among the photovoltaics research community, because of their high solar-to-electric power conversion efficiencies and low fabrication costs. [1,2] The employed metal-halide perovskites are solution-processable high-quality semiconductors with exceptional properties such as absorption over a wide spectrum, [3][4][5] a direct band gap, [6] and charge carrier diffusion lengths in the micrometer range. [7] These characteristics have enabled a broad range of possible applications ranging from perovskite solar cells (PSCs), [8] light-emitting diodes, [9] lasers, [10,11] photodetectors, [12,13] X-ray detectors, [14,15] to sensors. [16] In the past few years, organic-inorganic metal halide ABX 3 perovskites (A = Rb, Cs, methylammonium, formamidinium (FA); B = Pb, Sn; X = Cl, Br, I) have rapidly emerged as promising materials for photovoltaic applications. Tuning the film morphology by various deposition techniques and additives is crucial to achieve solar cells with high performance and long-term stability. In this work, carbon nanoparticles (CNPs) containing functional groups are added to the perovskite precursor solution for fabrication of fluorine-doped tin oxide/TiO 2 /perovskite/spiro-OMeTAD/gold devices. With the addition of CNPs, the perovskite films are thermally more stable, contain larger grains, and become more hydrophobic. NMR experiments provide strong evidence that the functional groups of the CNPs interact with FA cations already in the precursor solution. The fabricated solar cells show a power-conversion efficiency of 18% and negligible hysteresis.

Novel Surface Passivation for Stable FA0.85MA0.15PbI3 Perovskite Solar Cells with 21.6% Efficiency

“…As shown in Figure b, the peak near 8.78 ppm for the FAI solution w TPFPB additive is also split into two peaks similar to the splitting observed in the perovskite solution w TPFPB. The splitting of FA + protons into two new signals has also been observed by other research groups and us, and it is ascribed to the strong interaction between amino group (—NH 2 ) and TPFPB, as confirmed by very early reports . To further confirm the existence of F—H hydrogen bonds between TPFPB and FAI, we also measured the 19 F NMR spectra of TPFPB and TPFPB+FAI in the DMSO solution (Figure c).…”

Causes and Solutions of Recombination in Perovskite Solar Cells

“…It was also proposed that metal or halide ions could recrystallize the small grains and thereby passivate GBs and interface defects . Except for inorganic metal halide salts, hydrophobic carbon materials (including nitrogen‐doped reduced graphene oxide (N‐RGO) and carbon nanoparticles (CNPs)) were employed to control the grain size. Similar to the halide ions (including metal halide and organic halide salts) playing a key role in controlling and regulating the morphology and crystallization of perovskite films, pseudohalogen ions (especially for SCN − ) also can control and modulate the crystallization of perovskite films via its unique mechanism .…”

Bottom‐Up Synthesized MoS2 Interfacing Polymer Carbon Nanodots with Electrocatalytic Activity for Hydrogen Evolution

“…Their photochemical stability, solubility in both aqueous and organic solvents, and ease of fabrication by environmentally friendly means have attracted huge scientific attention during the last two decades. In particular, PCNDs can be easily obtained from cheap and chemically simple precursors, such as citric acid and polyamines, which are polymerized together by means of heating, acid treatment, or employment of catalysts . A photoinduced intramolecular charge‐transfer process between localized molecular states takes place on the polymeric structure of PCNDs results in strong fluorescent emission .…”

“…A photoinduced intramolecular charge‐transfer process between localized molecular states takes place on the polymeric structure of PCNDs results in strong fluorescent emission . This behavior has been fruitfully exploited for the implementation of PCNDs in donor–acceptor materials and for the preparation of prototype solar cells and LEDs …”