In Situ Reconstruction of Hole‐Selective Perovskite Heterojunction with Graded Energetics Toward Highly Efficient and Stable Solar Cells

Abstract

Perovskite solar cells (PSCs) have demonstrated a high power conversion efficiency, however, the large energy loss due to non‐radiative recombination is the main challenge for further performance enhancement. Here, a surface treatment strategy is developed by heat‐induced decomposition of a thin interlayer 2,7‐Naphthaleneditriflate (NAP) to in situ reconstruct perovskite energetics. It is verified that the reconstructed perovskite surface energetics match better with the upper hole transport layer compared to the intrinsic condition. Spontaneous generation of n/n− homojunctions between the perovskite film bulk and the surface region promotes hole extraction, enhancing built‐in electric field, and thus significantly suppresses charge recombination at such perovskite hole‐selective heterojunctions. Moreover, the surface decomposed fluorine‐rich complexes passivate the defects and improve the crystallinity of the perovskite film. These advantages are confirmed by a remarkably improved efficiency from 20.52% for the control device to 23.37% for the treated one with excellent stability. The work provides a promising approach of in situ reconstructing perovskite surface and interface for the design of highly efficient and stable PSCs.

Triisocyanate Derived Interlayer and High‐Melting‐Point Doping Promoter Boost Operational Stability of Perovskite Solar Cells

“…Post TTI modification, the formation of coordination bonds between C=O and Pb weakens the n‐type characteristics of the perovskite film. With an increased surface work function, the band can undergo an upward bend, mitigating electron accumulation at the interface between the perovskite and the hole transport layer upon photoexcitation, thereby suppressing interface charge recombination [15,47] …”

Modulation of Perovskite Surface Energetics for State‐of‐the‐Art Solar Cells

“…In a more recent study, Jiang et al treated the perovskite surface with a thin interlayer 2,7‐Naphthaleneditriflate (NAP), which induces an in situ reconstruction of perovskite surface energetics and leads to high‐performance PSCs. [ 85 ] The work function increases from 4.43 to 4.73 eV after NAP treatment (Figure 7g), contributed to the high electronegativity of fluorine in NAP. The IE keeps constant as the E F position with respect to the VBM downshifts from 1.18 to 0.90 eV.…”

Improved Photovoltaic Performance of Inverted Two-Dimensional Perovskite Solar Cells via a Simple Molecular Bridge on Buried Interface

“…Organic–inorganic halide perovskite solar cells (PSCs) have aroused broad research interest due to their remarkable photoelectric properties of high absorption coefficient, wide absorption range, tunable energy bandgap, as well as long charge carrier diffusion length. − Among them, the two-dimensional perovskite solar cells (2D-PSCs) are prepared by introducing organic spacer cations to partially replace methylamine ion (MA + ) or formamidine ion (FA + ) ions, which can greatly improve the wet stability and structure stability of the device. − Inverted 2D-PSCs achieved rapid development because of the matched energy level of the hole transport layer (HTL) and perovskite and their better perovskite morphology, thus obtaining higher photoelectric power conversion efficiency (PCE). , However, the inherent hygroscopic and acidic properties of PEDOT:PSS , and the poor solvent infiltration of PTAA, ,− which are the two most used HTL materials in inverted device, , impede the further development of photovoltaic performance and stability for inverted 2D-PSCs.…”