Nature: Breaking Barriers - 25.86% Efficiency Achieved in Methylamine-Doped Inverted Perovskite Solar Cells
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- Molecular Doping Process: The researchers introduced a molecular doping process using a dimethylamino-based dopant, which creates a well-matched p-perovskite/ITO contact and thoroughly passivates the grain boundaries. This innovative process boosts the power conversion efficiency (PCE) of the perovskite solar cells, achieving a certified PCE of 25.39%. This marks an improvement from the existing standards for perovskite solar cells.
- Molecular Squeezing Technique: The process involves a unique “molecular squeezing” method, in which the molecules are expelled from the precursor solution to the grain boundaries and the bottom of the film during the toluene-quenching crystallization process. This unique technique results in a p-doping of the perovskite film and contributes to the improvement in device efficiency.
- Longevity and Efficiency: The device achieved an efficiency of 25.86% (in reverse scanning) and demonstrated remarkable stability, maintaining 96.6% of its initial efficiency even after 1000 hours of light aging. This indicates a significant leap in the performance and reliability of perovskite solar cells.
In the rapidly advancing field of photovoltaics, the pursuit of harnessing solar energy more efficiently and sustainably remains an unwavering endeavor. Scientists have explored various approaches to improve the efficiency of solar cells, and among them, perovskite solar cells have consistently stood out due to their performance potential and cost-effective manufacturing capabilities. Today, we will focus on a significant breakthrough achieved by an exceptional research team led by Professor Zhubing He from Southern University of Science and Technology. They have achieved a profound enhancement in the efficiency of perovskite solar cells, marking an important step forward in our collective pursuit of a more sustainable and energy-efficient future.
This groundbreaking research introduces a novel molecular doping technique that differs fundamentally from conventional methods, utilizing a doping agent called dimethylamino group. This doping agent is ingeniously employed to form a compatible p-perovskite/ITO interface and selectively eliminate grain boundary defects, leading to a revolutionary improvement in the power conversion efficiency (PCE) of perovskite solar cells. The dedication and intellectual rigor of the research team have resulted in an astonishing world record of 25.39% certified PCE, setting new standards and possibilities in the industry.
To achieve this remarkable feat, the researchers proposed a clever technique known as “molecular squeezing.” This innovative strategy forces the molecules in the precursor solution to redistribute themselves at the grain boundaries and bottom film during the toluene quenching crystallization process. Consequently, this leads to p-type doping of the perovskite film, which is crucial for achieving a significant enhancement in device efficiency. This unique process thus signifies a foundational breakthrough that fundamentally alters the paradigm of renewable energy.
However, the triumph of this research extends beyond the realm of efficiency alone. The champion devices of the team not only demonstrated a PCE of 25.86% in reverse scans, surpassing previous thresholds, but also exhibited outstanding stability, maintaining 96.6% of their initial efficiency after 1000 hours of light aging. This achievement addresses a major challenge in perovskite solar cell technology—the balance between efficiency and stability—and provides a valuable foundation for future research aimed at optimizing these two critical aspects.
At the core of this groundbreaking research is the precise utilization of Enlitech’s QE-R precision measurement equipment. This advanced equipment provided the team with accurate readings, enabling them to carefully evaluate the outcomes of their novel approach. The choice of Enlitech’s QE-R device, renowned for its accuracy and reliability, underscores the importance of top-tier resources in achieving breakthrough results.
Furthermore, the researchers delved into the complex band alignment of the p-perovskite/ITO interface. By employing ultraviolet photoelectron spectroscopy (UPS), they elucidated the band bending phenomena that facilitate hole extraction, a key process for achieving high-performance solar cells. The experiments revealed that the dimethylamino group doping agent, along with molecular complexes formed with lead ions, modifies the work function of the ITO substrate, resulting in a band alignment favorable for efficient hole extraction.
In addition to the improvements in efficiency and stability, the research team also addressed the challenge of hysteresis commonly observed in perovskite solar cells. Through the adoption of molecular squeezing technique and precise doping engineering, they significantly mitigated hysteresis, making the device performance more reliable and reproducible. This breakthrough offers tremendous potential for practical application and commercialization of perovskite solar cells, as it tackles one of the major obstacles hindering their widespread implementation.
Furthermore, the detailed investigation of charge carrier dynamics by the research team revealed the exceptional mechanisms behind the outstanding performance of their perovskite solar cells. Through various analytical techniques, including charge density difference and Bader charge analysis, they unveiled the redistribution of charges within the perovskite film , attributed to the effective molecular doping strategy. This redistribution resulted in improved hole extraction efficiency and enhanced overall device performance.
In conclusion, this groundbreaking research represents a significant advancement in the field of perovskite solar cells, achieving a record-breaking efficiency of 25.39% and demonstrating outstanding stability. The combination of molecular doping techniques and innovative molecular squeezing technology paves the way for unprecedented control over device performance and stability. The utilization of Enlitech’s QE-R precision measurement equipment played a crucial role in accurately assessing the optoelectronic properties of the fabricated devices. This extraordinary achievement brings us closer to unlocking the full potential of perovskite solar cells, propelling us towards a future driven by clean and renewable energy.
XPS spectra of Pb 4f (a), I 3d (b) and P 2p (c) at the detached ITO surface
from ITO/DMAcPA/Perovskite (blue) and ITO/Perovskite(DMAcPA) (red) samples.
Figure S26. XPS spectra of Pb 4f (a), I 3d (b) and survey (c), detected at the bottom surfaces of pristine (red) and DMAcPA dopped (blue)perovskite films, identical to the fabrication process reported in the main text. The red shift in binding energy of Pb25
detected at the buried bottom surface of perovskite (Fig. S26a) can also indicate the O–Pb dative bond weakens the binding energy of the main-flow Pb-I covalent bond and herein accounts for the red shift of Pb. Regarding the I shift (Fig. S26b), it can be attributed to hydrogen bonding of P-O-H–I, which has been well discussed and examined by the above down-field chemical shift of 1H NMR signal (Fig. 3A).
Key Word: Methylamine, inverted perovskite solar cells, passivating grain boundaries, perovskite thin films