Efficient and Stable Wide‐Bandgap Perovskite Solar Cells Derived from a Thermodynamic Phase‐Pure Intermediate

Abstract

Wide‐bandgap perovskites based on alloying cesium and formamidinium lead mixed halides (Cs x FA1–x Pb(I y Br1–y )3) have received great attention due to their potential application in high‐efficiency tandem solar cells. However, the fast crystallization of Cs x FA1–x Pb(I y Br1–y )3 perovskite films results in a high trap density and hinders the further enhancement of the photovoltaic performance. Herein, an intermediate engineering is developed to retard the fast crystallization of Cs0.17FA0.83PbI1.8Br1.2 wide‐bandgap perovskite by adding FACl in the precursor solution. The introduction of the FACl additive leads to the formation of a thermodynamic phase‐pure intermediate which facilitates the further crystallization of a high‐quality perovskite thin film at elevated temperature and thus enhances the ultimate device performance. The champion device achieves an efficiency over 19% and exhibits 83.8% retention after 50 days aging without encapsulation.

Crack‐Free Monolayer Graphene Interlayer for Improving Perovskite Crystallinity and Energy Level Alignment in Efficient Inverted Perovskite Solar Cells

“…In PSCs, perovskite film is sandwiched between the electron‐transport layer (ETL) and hole‐transport layer (HTL). [ 4 ] In perovskite film, the electron–hole pairs are generated after capturing photons, then separated and transported into the ETL and HTL, respectively, and finally collected through both two electrodes as photocurrent. [ 5 ] In the aforementioned working process, the perovskite crystallinity and energy level alignment are critical to the photovoltaic parameters of PSCs, such as open‐circuit voltage ( V OC ), and short‐circuit current ( J SC ), and fill factor (FF).…”

Composites of cross-linked perovskite/polymer with sodium borate for efficient and stable perovskite solar cells

“…4,5 There are several approaches to improve the performance of PSCs, such as composition engineering of perovskite materials and additive engineering of the perovskite precursor. 6,7 The compositional engineering approach, including the use of triple or quadruple cations, the chemical modication of the X site anions of Br or Cl ions, and the inclusion of various metal halide salts in the perovskite precursor for reducing defects and manipulating the lm morphology, has been the method of choice to date. 8,9 In addition, the inclusion of alkali salts like Li + , Na + , K + , and Rb + has been adopted as an attractive strategy to achieve highly uniform grains for enhancing the stability by partially replacing formamidinium (FA + ) or methylammonium (MA + ) with these ions.…”

Bulk heterojunction organic photovoltaic cells based on D–A type BODIPY small molecules as non-fullerene acceptors

“…9–11 However, some disadvantages of fullerene acceptor materials limit the further improvement of organic solar energy performance, including weak light absorption and insufficient utilization in the visible region, difficult preparation and purification, high synthesis cost, and poor energy level adjustment. 12–16 Therefore, the development of new electron acceptor materials to replace fullerene derivatives has become a new focus in the field of organic solar cell research. In this regard, non-fullerene small molecule acceptors ( NFSMAs ) have shown significant advantages due to their low synthesis cost, strong absorption of the solar spectrum in the visible region, higher stability, easy adjustable energy levels, and higher open circuit voltage over fullerene-based acceptor materials.…”