Sulfide kesterite Cu 2 ZnSnS 4 (CZTS)—a non-toxic and low-cost photovoltaic material—has always faced severe charge recombination and poor carrier transport, resulting in its cell efficiency record stagnating at around 11% for years. The implementation of gradient bandgaps is a promising approach to relieving these issues, but it has not been effectively realized in kesterite solar cells due to challenges around controlling the elemental distribution. Here, based on Cd-alloyed CZTS, we propose a pre-crystallization strategy to reduce the intense vertical mass transport and Cd rapid diffusion in the film growth process, thereby realizing a Cd-gradient CZTS absorber. This absorber, exhibiting a downward-bent conduction band structure, effectively enhances the bulk carrier transport and additionally improves the interface properties of the CZTS/CdS heterojunction. These benefits significantly enhance the photoelectric conversion performance of the cell and help in achieving a certified total-area cell efficiency of about 13.2% with obviously reduced voltage loss, realizing a substantial step forward for the pure-sulfide kesterite solar cell.
Miniaturized multispectral detectors are urgently desired given the unprecedented prosperity of smart optoelectronic chips for integrated functions including communication, imaging, scientific analysis, etc. However, multispectral detectors require complicated prism optics or interference/interferometric filters for spectral recognition, which hampers the miniaturization and their subsequent integration in photonic integrated circuits. In this work, inspired by the advance of computational imaging, optical-component-free miniaturized multispectral detector on 4 mm gradient bandgap MAPbX 3 microwire with a diameter of 30 µm, is reported. With accurate composition engineering, halide ions in MAPbX 3 microwire vary from Cl to I giving in the gradual variation of optical bandgap from 2.96 to 1.68 eV along axis. The sensing units on MAPbX 3 microwire offer the response edge ranging from 450 to 790 nm with the responsivity over 20 mA W −1 , −3dB width over 450 Hz, LDR of ≈60 dB, and a noise current less than ≈1.4 × 10 −12 A Hz −0.5 . As a result, the derived miniaturized detector achieves the function of multispectral sensing and discrimination with spectral resolution of ≈25 nm and mismatch of ≈10 nm. Finally, the proof-of-concept colorful imaging is successfully conducted with the miniaturized multispectral detector to further confirm its application in spectral recognition.
危险品化学品经营许可证（带存储）