Polishing the Lead‐Poor Surface for Efficient Inverted CsPbI 3 Perovskite Solar Cells

Guo

et al. 2022

Small

device stability. [3][4][5][6][7] Moreover, noble metal electrodes could increase the production costs. [8] Therefore, carbon-based inorganic PSCs (C-IPSCs) with a simple HTL-free architecture have attracted extensive attention, in view of their low costs, simple fabrication process, and excellent long-term stability. [5,9,10] Mixed-halide CsPbI 2 Br perovskite is an appealing photovoltaic material due to its good trade-off between band gap (E g ) and phase stability. [11,12] However, the PCEs of reported CsPbI 2 Br C-IPSCs are still far from their counterparts based on the organic HTLs and noble metal electrodes owing to bulk defects and interfacial energy level mismatch. [5] To address these issues, composition and additive engineering have been widely used to optimize perovskite quality and passivate film defects. [13][14][15][16] Besides, some functional materials are also employed as the interlayers to adjust the energy level alignment of CsPbI 2 Br/carbon interface. [10,[17][18][19] Unfortunately, the above studies mainly focus on the perovskite or its top interface modification, while ignoring the electron transport layer (ETL)/CsPbI 2 Br buried interface. Actually, the defects at the bottom interface is even higher than that on top, due to the accumulation of deep level defects, which will cause poor electron transport and severe ion migration, resulting in current density-voltage (J-V) hysteresis and device instability issues. [8,11,20,21] Regarding the typical ETLs such as tin oxide (SnO 2 ) and titanium oxide (TiO 2 ) nanoparticles, up to 30% of the atomic bonds are dangling bonds, which will cause a large number of oxygen defects (O defects ) including oxygen vacancies (O v ) and surface hydroxyl (OH) groups defects (O OH )). [11,22,23] Meanwhile, these dangling states are considered fatal, because the imperfect lattice arrangements can damage its electronic properties, resulting in charge recombination and energy level mismatch with perovskite films. [11,21] On the other hand, interfacial strain and lattice distortion are inevitable during the rapid crystallization process of perovskite films, which have a significant effect on the defect formation energy, carrier mobility, energy level structure, and ion migration. [24,25] Simultaneously, the interfacial residual stress at the bottom of perovskite films is also the reason for accelerated material degeneration. [26] On account of The charge recombination resulting from bulk defects and interfacial energy level mismatch hinders the improvement of the power conversion efficiency (PCE) and stability of carbon-based inorganic perovskite solar cells (C-IPSCs).Herein, a series of small molecules including ethylenediaminetetraacetic acid (EDTA) and its derivatives (EDTA-Na and EDTA-K) are studied to functionalize the zinc oxide (ZnO) interlayers at the SnO 2 /CsPbI 2 Br buried interface to boost the photovoltaic performance of low-temperature C-IPSCs. This strategy can simultaneously passivate defects in ZnO and perovskite films, adjust interfacial energy ...

Section: Resultssupporting

confidence: 52%

Small Molecules Functionalized Zinc Oxide Interlayers for High Performance Low‐Temperature Carbon‐Based CsPbI₂Br Perovskite Solar Cells

Guo

et al. 2022

Small

“…The higher V bi values can give rise to a larger driving force for charge separation and induce an expanded depletion region to suppress interfacial charge accumulation/recombination, which is the main reason for the increased V oc and reduced J-V hysteresis in the modied devices. 14,70,71 We ascribed the increased V bi values to the adjusted interfacial energy level alignment at the ETL/ perovskite interface (Fig. S33b, ESI †).…”

Section: Resultsmentioning

confidence: 99%

Targeting the imperfections at the ZnO/CsPbI₂Br interface for low-temperature carbon-based perovskite solar cells

Guo

et al. 2023

J. Mater. Chem. A

“…The Fermi level of the control CsPbI 3 films was close to the VBM (0.74 eV), indicating the p-type nature. 47 When contacting PCBM, the Δ E CBM of the CsPbI 3 and PCBM was 0.35 eV, and the large energy level mismatch may lead to the formation of a huge energy-level gap and serious non-radiative recombination at the interface.…”

Section: Resultsmentioning

confidence: 99%

Surface n-type band bending for stable inverted CsPbI₃perovskite solar cells with over 20% efficiency

Wang

et al. 2023

Energy Environ. Sci.