Quantifying the Interface Defect for the Stability Origin of Perovskite Solar Cells

Abstract

The stability issue that is obstructing commercialization of the perovskite solar cell is widely recognized, and tremendous effort has been dedicated to solving this issue. However, beyond the apparent thermal and moisture stability, more intrinsic semiconductor mechanisms regarding defect behavior have yet to be explored and understood. Herein, defects are quantified; especially interface defects, within the cell to reveal their impact on device performance and especially stability. Both the bulk and interface defects are distinguished and traced in situ using an expanded admittance model when the cell degrades in its efficiency under illumination or voltage. The electric field‐induced interface, rather than bulk defects, is found to have a direct correlation to stability. Releasing the interface strain using a fullerene derivative is an effective way to suppress interface defect formation and improve stability. Overall, this work provides a quantitative approach to probing the semiconductor mechanism behind the stability issue, and the inherent correlation discovered here among the electric field, interface strain, interface defects, and cell stability has important implications for ongoing device stability engineering.

Intermolecular π–π Conjugation Self‐Assembly to Stabilize Surface Passivation of Highly Efficient Perovskite Solar Cells

“…In addition, we further studied the interface defect properties via a modified equivalent circuit model (Figure S13, Supporting Information). [ 17 ] According to the fitting results, the interface defect density of TBPO is found to be 3.4 × 10 12 cm −2 eV −1 , which is obviously smaller than that of both the control group (6.0 × 10 12 cm −2 eV −1 ) and the TPPO passivated cell (4.6 × 10 12 cm −2 eV −1 ). The results show that interface defects are suppressed.…”

Toward Efficient and Stable Perovskite Solar Cells: Choosing Appropriate Passivator to Specific Defects

“…A large number of studies have observed that MA + or I − ions were capable of migration under illumination or an applied electric field within the perovskite films. The migration of mobile ions may cause many adverse effects including band bending, [ 47,50,161 ] J–V hysteresis, [ 162,163 ] lattice strain, [ 102 ] reaction with neighboring function layers, [ 164–166 ] and phase segregation, [ 154,167,168 ] thereby seriously impacting the carrier extraction efficiency and the photoelectric performance of PSCs. During the device operation, the photogenerated field inside the PSC may drive the positively (or negatively) charged defects to migrate toward the HTL (or electron transport layer [ETL]).…”

“…Inserting a fullerene derivative [ 6, 6 ]‐phenyl‐C61‐butyric acid (PCBA) film can significantly relieve interface stress and reduce the generation of interface defects. [ 102 ] Movable ions that migrate to the device interface may react chemically with neighboring functional layers leading to device degradation. [ 50 ] In addition, the undesirable reaction between I − in the perovskite film and Spiro‐OMeTAD + molecules was observed by Carrillo et al This caused a decrease in the conductivity of HTL and a deterioration of device performance.…”

Insight into the Origins of Figures of Merit and Design Strategies for Organic/Inorganic Lead‐Halide Perovskite Solar Cells

“…[99c] The specific R s and R sh values could be extracted from the J-V fitting or impedance spectra. [38,103] Furthermore, under device-operating conditions, these resistances become a function of the bulk and interfacial transport of photogenerated carriers. Based on the origin of the FF and aforementioned analyses, carrier management should be considered in detail.…”