Enhancing the Performance of Inverted Perovskite Solar Cells via Grain Boundary Passivation with Carbon Quantum Dots

Abstract

Nonradiative recombination, the main energy loss channel for open circuit voltage (V oc), is one of the crucial problems for achieving high power conversion efficiency (PCE) in inverted perovskite solar cells (PSCs). Usually, grain boundary passivation is considered as an effective way to reduce nonradiative recombination because the defects (uncoordinated ions) on grain boundaries are passivated. We added the hydroxyl and carbonyl functional groups containing carbon quantum dots (CQDs) into a perovskite precursor solution to passivate the uncoordinated lead ions on grain boundaries. Higher photoluminescence intensity and longer carrier lifetime were demonstrated in the perovskite film with the CQD additive. This confirmed that the addition of CQDs can reduce nonradiative recombination by grain boundary passivation. Additionally, the introduction of CQDs could increase the thickness of the perovskite film. Consequently, we achieved a champion device with a PCE of 18.24%. The device with CQDs retained 73.4% of its initial PCE after being aged for 48 h under 80% humidity in the dark at room temperature. Our findings reveal the mechanisms of how CQDs passivate the grain boundaries of perovskite, which can improve the efficiency and stability of PSCs.

Laser‐Generated Supranano Liquid Metal as Efficient Electron Mediator in Hybrid Perovskite Solar Cells

“…After introducing the LMCs, the CsFAMA‐LMCs films displays a similar phase and crystal structure to those of the CsFAMA films, and no shift of the diffraction peaks could be observed (X‐ray diffraction (XRD), Figure 3c). This suggests that the supranano‐LMCs do not enter the perovskite lattice, [ 21 ] but are mostly distributed at the surface and GBs, [ 22 ] as schematically illustrated in Figure 3a.…”

“…The shortened PL decay indicates a faster electron‐transfer process and more efficient electron extraction, as evidenced by the PL quenching, which suggests that the supranano‐LMCs are helpful for charge separation in perovskite film. [ 22,25 ]…”

Energy Level Modification with Carbon Dot Interlayers Enables Efficient Perovskite Solar Cells and Quantum Dot Based Light‐Emitting Diodes

“…Carbon dots (CDs) are known as cheap, stable, abundant, and easily‐to‐synthesized nanomaterials with high visible light transmittance; they have been already employed as interface modifiers in some optoelectronic devices, such as polymer, perovskite and crystalline silicon solar cells, and as hole injection layers in perovskite LEDs . Very recently, blue‐emitting CDs and multicolored CDs with narrow bandwidth emission have displayed an impressive electroluminescence performance, demonstrating their great potential as light‐emitting layers of LEDs.…”

Black Phosphorus Quantum Dots Induced High‐Quality Perovskite Film for Efficient and Thermally Stable Planar Perovskite Solar Cells

“…To acquire high‐quality perovskite films, researchers have developed a number of preparation strategies. Among these, the additive‐assisted growth method has been widely exploited and shown to be effective . For example, Liu and co‐workers have introduced semiconducting molecules with Lewis acid or base functional groups into the perovskite absorber, leading to an improved PCE of 19.3% and better environmental stability .…”

“…Sulfonic zwitterion was adopted by Huang's group for crystallization control and defect passivation, which resulted in a high PCE of 21.1% for mixed‐cations PVSCs . Recently, Huang's group has introduced carbon quantum dots as additives in PVSCs for grain boundary passivation, yielding an improved PCE of 18.24% and better stability …”