Azo‐Initiator‐Induced Cascade Defect Passivation for Efficient and Stable Planar Perovskite Solar Cells

Abstract

Remarkable progress in perovskite solar cells (PSCs) has been made by virtue of surface and bulk modification for defect control of perovskite layers, however, the interior defects in the perovskite layer can be hardly passivated by means of conventional passivation strategies, which makes perovskites prone to decomposition with inferior device performance. Here, the authors propose a cascade defect passivation strategy to doubly reduce perovskite defects by introducing a series of azo radical initiators. The primary passivation process of the azo compounds is realized on the perovskite surfaces through strong coordination interactions between Pb2+ and carbonyl/cyano groups. The secondary passivation occurs after thermal treatment, and the decomposed products diffuse into the interior defects of the initial passivated perovskite films through grain boundaries to accomplish the cascade defect passivation. Excitingly, this passivation strategy inhibits unwanted defect‐assisted recombination effectively, and thus CH3NH3PbI3 (MAPbI3)‐based inverted PSCs exhibit a significant increase in power conversion efficiency (PCE) from 16.92% to 19.69%. Moreover, the dual‐passivated PSCs show only 10% PCE loss after 3000 h in an inert atmosphere. Overall, the first proposed cascade defect passivation strategy is highly efficient in promoting defect healing of perovskites, demonstrating a new way to prepare high‐quality perovskite films for high‐performance PSCs.

Kinetic Control of Solvate Intermediate Evolution for High-Performance Perovskite Solar Cells by the Facial Mask Incubation Technique

“…As illustrated in Figure a,b, stronger PL intensity and prolonged carrier lifetime (69 and 116 ns for control and FM film, respectively) were observed in FM film, suggesting effective suppression of undesired nonradiative recombination. The enhanced carrier lifetime can be attributed to the optimized crystal morphology and improved phase purity of the FM-based film, which provide reduced electronic defect states for efficient charge transport . To further investigate the electrical properties, Kelvin probe force microscopy (KPFM) measurements were conducted (Figure c).…”

“…The enhanced carrier lifetime can be attributed to the optimized crystal morphology and improved phase purity of the FM-based film, which provide reduced electronic defect states for efficient charge transport. 27 To further investigate the electrical properties, Kelvin probe force microscopy (KPFM) measurements were conducted (Figure 3c). Compared to the control one, the FM film shows a more uniform surface potential arising from efficient defect passivation, which contributes to suppressing band bending and accelerating electron extraction at the perovskite/electron transport layer interface.…”

Enhancement in the Efficiency of Sb2Se3 Solar Cells by Triple Function of Lithium Hydroxide Modified at the Back Contact Interface

“…The results demonstrate that the Sb─O bonds disappeared when the etching depth reached 100 nm, indicating that the Sb─O layer only exists on the surface of the Sb 2 Se 3 film. [31] Additionally, the Li‐ion signal was detected even when the etching depth had reached 100 nm. The TOF‐SIMS results in Figure 4d indicate that the Li‐ion signal can be detected throughout the entire Sb 2 Se 3 thin film.…”

Incubating High‐Quality Perovskite Film via Facial Mask Technique for Efficient and Stable Solar Cells

“…Moreover, in the cross‐sectional SEM (Figure 3a–c), the perovskite films fabricated by FM incubation strategy exhibit better grain orientation, and no horizontal stratification of grains is observed for FM‐PEAI device, which is critical to the construction of efficient vertical carrier transport channels. [ 18 ] Furthermore, a significantly reduced surface root‐mean‐square (RMS) roughness from 20.2 nm (Control) to 12.5 nm (FM‐MAI) and 12.4 nm (FM‐PEAI) is observed upon FM incubation treatment (Figure 3d–f), implying that FM incubation strategy is also conducive to the formation of smoother perovskite surface. [ 19 ] In addition, the morphological characterization of pure PDMS‐treated perovskite film without solution immersion also exhibits similar evolution (Figure S10, Supporting Information).…”