Selective Defect Passivation and Topographical Control of 4‐Dimethylaminopyridine at Grain Boundary for Efficient and Stable Planar Perovskite Solar Cells

Abstract

Recent progress in highly efficient perovskite solar cells (PSCs) has been made by virtue of interfacial engineering on 3D perovskite surfaces for their defect control, however, the structural stability of the modified interface against external stimuli still remains unresolved. Herein, 4‐dimethylaminopyridine (DMAP) is introduced to develop a facile technique for selectively passivating the grain boundary (GB) and controlling the topographical boundary of the perovskite surface near the GB. Through the surface treatment of DMAP, strongly bound DMAP crystals are selectively formed at the GB, which serves two functions: nonradiative recombination at GB is effectively reduced by healing the uncoordinated Pb2+ while adhesion strength between the perovskite and the poly(triaryl amine) (PTAA) polymer is significantly enhanced by a mechanical interlock effect. A planar PSC with DMAP treatment exhibits a champion power conversion efficiency of 22.4%, which is not only much higher than the 20.04% observed for a nontreated control device, but also the highest among the planar PSCs using PTAA polymers as a hole transport material. Furthermore, the use of DMAP leads to a substantial improvement in the device stability under damp‐heat test and light irradiation.

Defect Passivation through Cyclohexylethylamine Post-treatment for High-Performance and Stable Perovskite Solar Cells

“…47 This result suggested that the amine functional group with a lone pair of electrons in CHEA could effectively passivate Pb 2+ sites on the surface of the perovskite film. 48 In addition, the peak of CO at 288.3 eV of the CHEA-passivated sample decreased significantly compared with that of the pristine sample, which can be due to the fact that CHEA can protect the 3D perovskite from oxygen and moisture in the environment. 49,50 This result indicated that the air stability of the PSCs was enhanced by passivation with CHEA.…”

Binary Additive Engineering Enables Efficient Perovskite Solar Cells via Spray-Coating in Air

“…Obvious wide boundaries between adjacent grains can be observed in the reference film. According to previous studies, , the defects in grain boundaries will lead to nonradiative recombination and are harmful to carrier transport and collection, while the wide grain boundaries between the large grains would further aggravate these negative effects, resulting in inefficient devices. Encouragingly, the quality of the L-α-P based perovskite film (Figure b) is significantly improved, where the large grains are more tightly packed and the grain boundaries are narrowed dramatically.…”

Thiamine additive engineering enables improved film formation towards high efficiency and moisture stability in perovskite solar cells

“…For the pure perovskite film (Fig. 2d), the peaks at 143.28 and 138.38 eV are indexed to Pb 2+ [36][37][38][39]. The two weak satellite peaks at 136.68 and 141.58 eV are assigned to metallic Pb (Pb 0 ), which is caused by unsaturated lead.…”