The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination. In addition, poor perovskite crystallization and incomplete conversion of PbI2 to perovskite restrict further enhancement of the photovoltaic performance of the devices using sequential deposition. Herein, a buried interface stabilization strategy that relies on the synergy of fluorine (F) and sulfonyl (S=O) functional groups is proposed. A series of potassium salts containing halide and non-halogen anions are employed to modify SnO2/perovskite buried interface. Multiple chemical bonds including hydrogen bond, coordination bond and ionic bond are realized, which strengthens interfacial contact and defect passivation effect. The chemical interaction between modification molecules and perovskite along with SnO2 heightens incessantly as the number of S=O and F augments. The chemical interaction strength between modifiers and perovskite as well as SnO2 gradually increases with the increase in the number of S=O and F. The defect passivation effect is positively correlated with the chemical interaction strength. The crystallization kinetics is regulated through the compromise between chemical interaction strength and wettability of substrates. Compared with Cl-, all non-halogen anions perform better in crystallization optimization, energy band regulation and defect passivation. The device with potassium bis (fluorosulfonyl) imide achieves a tempting efficiency of 24.17%. 

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Stabilizing Buried Interface via Synergistic Effect of Fluorine and Sulfonyl Functional Groups Toward Efficient and Stable Perovskite Solar Cells

Over the past few years, all‐inorganic perovskite solar cells (PSCs), especially CsPbI2Br PSCs, have received much attention because of their excellent thermal stability and a suitable trade‐off between light absorption and higher phase stability among the family of inorganic perovskites. In this progress report, the realization of highly efficient and stable CsPbI2Br PSCs is summarized through preparation process, additive engineering, interface modification, and transport material selection. Furthermore, the application of CsPbI2Br in tandem solar cells and its large‐area development are highlighted. Finally, the challenges and outlook of CsPbI2Br PSCs are discussed for further performance improvement and future practical deployment.

Progress and Perspective on Inorganic CsPbI2Br Perovskite Solar Cells

Following the 2nd release of the “Emerging PV reports,” the best achievements in the performance of emerging photovoltaic devices in diverse emerging photovoltaic research subjects are summarized, as reported in peer‐reviewed articles in academic journals since August 2021. Updated graphs, tables, and analyses are provided with several performance parameters, e.g., power conversion efficiency, open‐circuit voltage, short‐circuit current density, fill factor, light utilization efficiency, and stability test energy yield. These parameters are presented as a function of the photovoltaic bandgap energy and the average visible transmittance for each technology and application, and are put into perspective using, e.g., the detailed balance efficiency limit. The 3rd installment of the “Emerging PV reports” extends the scope toward triple junction solar cells.

Device Performance of Emerging Photovoltaic Materials (Version 3)

Recent progress in perovskite solar cells: from device to commercialization

Monolithic perovskite/black-silicon tandems based on tunnel oxide passivated contacts

A universal close-space annealing strategy towards high-quality perovskite absorbers enabling efficient all-perovskite tandem solar cells

Perovskite solar cells suffer from poor reproducibility due to the degradation of perovskite precursor solution. Herein, we report an effective precursor stabilization strategy via incorporating 3-hydrazinobenzoic acid (3-HBA) containing carboxyl (-COOH) and hydrazine (-NHNH 2 ) functional groups stabilizer. The oxidation of I - , deprotonation of organic cations and amine-cation reaction are main causes of the degradation of mixed organic cation perovskite precursor solution. The -NHNH 2 can reduce I 2 defects back to I - and thus suppress the oxidation of I - , while the H + generated by -COOH can inhibit the deprotonation of organic cations and subsequent amine-cation reaction. The above degradation reactions are simultaneously inhibited by the synergy of functional groups. The inverted device achieves an efficiency of 23.5% (certified efficiency of 23.3%) with excellent operational stability, retaining 94% of the initial efficiency after maximum power point tracking for 601 hours.

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Stabilizing Perovskite Precursor by Synergy of Functional Groups for NiOx-Based Inverted Solar Cells with 23.5% Efficiency.

Perovskite solar cells suffer from poor reproducibility due to the degradation of perovskite precursor solution. Herein, we report an effective precursor stabilization strategy via incorporating 3-hydrazinobenzoic acid (3-HBA) containing carboxyl (−COOH) and hydrazine (−NHNH2) functional groups as stabilizer. The oxidation of I−, deprotonation of organic cations and amine-cation reaction are the main causes of the degradation of mixed organic cation perovskite precursor solution. The −NHNH2 can reduce I2 defects back to I− and thus suppress the oxidation of I−, while the H+ generated by −COOH can inhibit the deprotonation of organic cations and subsequent amine-cation reaction. The above degradation reactions are simultaneously inhibited by the synergy of functional groups. The inverted device achieves an efficiency of 23.5 % (certified efficiency of 23.3 %) with an excellent operational stability, retaining 94 % of the initial efficiency after maximum power point tracking for 601 hours. 

/pdf/stabilizing-perovskite-precursor-by-synergy-of-functional-hmlk2ffd.pdf

Cong Chen

Papers

A universal close-space annealing strategy towards high-quality perovskite absorbers enabling efficient all-perovskite tandem solar cells

Stabilizing Perovskite Precursor by Synergy of Functional Groups for NiOx-Based Inverted Solar Cells with 23.5% Efficiency.

Stabilizing Perovskite Precursor by Synergy of Functional Groups for NiOx‐Based Inverted Solar Cells with 23.5% Efficiency

Recent progress in perovskite solar cells: from device to commercialization

Pre-annealing treatment for high-efficiency perovskite solar cells via sequential deposition