Effects of Ge Alloying on Device Characteristics of Kesterite-Based CZTSSe Thin Film Solar Cells

The impacts of Ge alloying on crystal growth and device properties of kesterite-based CZTSSe thin film solar cells fabricated by chalcogenization of sputtered stacks in S/Se ambient were investigated. It was found that Ge-alloyed CZTSSe material improved the grain growth, compactness of film texture, and crystallinity of absorber layers as a consequence of the device efficiencies were enhanced from ∼3 to 6%. The investigations on optoelectronic characteristics of devices illustrated that the improvements in devices were mainly governed by decrease in diode ideality factor, suppression of crossover effect between white and dark <i>J</i>–<i>V</i> curves, and reduction of defect level in Ge-alloyed CZTSSe solar cell device. These results suggest the possibility to achieve a further improvement in the optoelectronic characteristics of the devices that could be accomplished by optimization of the technological processes with a fine-tuning of the Ge content in the layers

A Nonvacuum Approach for Fabrication of Cu₂ZnSnSe₄/In₂S₃ Thin Film Solar Cell and Optoelectronic Characterization

Cd-free kesterite-based Cu₂ZnSnSe₄ (CZTSe)/In₂S₃ champion solar cell of 5.74% efficiency has been fabricated by chemical spray pyrolysis. In this fabrication route, CZTSe absorber layer was sprayed by using a precursor solution, where metallic salts were dissolved in water-based solvent and subsequently selenized with Se powder at high temperature. In₂S₃ buffer as an alternative to CdS buffer was also deposited by chemical spray pyrolysis. The device characteristics were studied by measuring dark/light illuminated <i>J</i>–<i>V</i>–<i>T</i>, external quantum efficiency, temperature dependence of open circuit voltage (<i>V</i>_OC) and series resistance (<i>R</i>_s), and admittance spectroscopy. The performance of sprayed CZTSe/In₂S₃ solar cell was found to be limited by high back-contact barrier potential, poor carrier collection, and detrimental intrinsic defect states in device

Defect passivation in methylammonium/bromine free inverted perovskite solar cells using charge-modulated molecular bonding

Abstract Molecular passivation is a prominent approach for improving the performance and operation stability of halide perovskite solar cells (HPSCs). Herein, we reveal discernible effects of diammonium molecules with either an aryl or alkyl core onto Methylammonium-free perovskites. Piperazine dihydriodide (PZDI), characterized by an alkyl core-electron cloud-rich-NH terminal, proves effective in mitigating surface and bulk defects and modifying surface chemistry or interfacial energy band, ultimately leading to improved carrier extraction. Benefiting from superior PZDI passivation, the device achieves an impressive efficiency of 23.17% (area ~1 cm2) (low open circuit voltage deficit ~0.327 V) along with superior operational stability. We achieve a certified efficiency of ~21.47% (area ~1.024 cm2) for inverted HPSC. PZDI strengthens adhesion to the perovskite via -NH2I and Mulliken charge distribution. Device analysis corroborates that stronger bonding interaction attenuates the defect densities and suppresses ion migration. This work underscores the crucial role of bifunctional molecules with stronger surface adsorption in defect mitigation, setting the stage for the design of charge-regulated molecular passivation to enhance the performance and stability of HPSC