Chemical passivation of ionic defects in perovskite materials is an effective strategy to reduce charge recombination in perovskite solar cells (PSCs). Although several additives have been used for this purpose, the passivation mechanisms of different functional groups have remained unclear. Herein, the effect of molecules possessing multiple functional anchoring is systematically investigated. Three different multifunctional molecules namely 5‐aminoisophthalic acid (AIA), 5‐hydroxyisophthalic acid (HIA), and chelidamic acid (CA) are strategically chosen. These molecules not only take part in the crystallization process but also passivate the trap states effectively. CA shows superior passivation capacity among all with a better dipolar electron density distribution. The passivated films have considerably improved morphology with fewer pin holes, larger grains, and lower trap states in comparison to the pristine film. CA‐passivated p–i–n structured photovoltaic devices demonstrate the best power conversion efficiency (PCE) of 19.06% with an impressive open circuit voltage (VOC) of 1.097 V, whereas pristine devices show a PCE of 13.60% and VOC of 0.972 V. Moreover, the modified device reveals notable thermal and ambient stability in comparison to the pristine device due to lower defect states and reduced ion migration.
Recently, organic-inorganic hybrid perovskite solar cells (PSCs) have experienced a rapid growth in terms of efficiency. However, the instability of hybrid perovskite materials towards ambient conditions restricts its commercialization. Formation...
Developing large-scale perovskite solar cells requires highquality defect-free perovskite films with improved surface coverage. One of the most convenient ways to achieve this is through the incorporation of appropriate passivation molecules in the perovskite films. Herein, the effect of a novel conjugated polyelectrolyte, PHIA, is investigated for perovskite passivation by the comprehensive analysis of perovskite films and devices. The PHIA polymer significantly diminishes the trap states in perovskite films, and the passivated device permits lesser recombination, very low accumulation of charges at the interface, and lowers the traps which facilitated superior charge transport. As a result, a high power conversion efficiency of 20.17% has been achieved for the PHIA-modified device. Additionally, this passivation approach effectively enhanced the long-term device stability by improving the hydrophobicity of the perovskite layer. Furthermore, a large-area device (2 cm 2 ) has also been fabricated to demonstrate the expediency of this approach for future commercialization.
Trap
state formation in perovskite films during their preparation
is a key limitation restricting the device performance and stability
of perovskite solar cells. These trap states are generally present
at the surface of perovskite films and on grain boundaries and work
as charge recombination centers, thereby influencing the device performance.
Hence, regulating these detrimental trap states that are susceptible
to deformation is vital for improving the solar cell performance.
Herein, a unique methodology of trap states passivation has been demonstrated
using multiple carboxylic acid-functionalized small aromatic molecules.
Three additives, viz., benzene carboxylic acid (BCA), benzene-1,3-dicarboxylic
acid (BDCA), and benzene-1,3,5-tricarboxylic acid (BTCA), have been
utilized as additives in the precursor solution that reduced trap
states in the perovskite films. Perovskite films generated in the
presence of these additives strongly influence the charge transfer
dynamics and result in improved performance and stability of the devices
by lowering the photogenerated charge recombination. BTCA-incorporated
devices result in the highest power conversion efficiency (PCE) of
18.30% with a significant improvement in the open-circuit voltage
(V
oc) to 1075.9 mV (an enhancement of
≈80 mV) compared to the control device. Additionally, the devices
also show enhanced thermal stability.
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