Reduced recombination through the CZTS/CdS interface engineering in monograin layer solar cells
| Main Authors: | Kauk-Kuusik, Marit, Timmo, Kristi, Muska, Katri, Pilvet, Maris, Krustok, Jüri, Danilson, Mati, Mikli, Valdek, Josepson, Raavo, Grossberg-Kuusk, Maarja |
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| Format: | Article Journal |
| Terbitan: |
, 2022
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/6443020 |
Daftar Isi:
- Abstract The power conversion efficiency of CZTS solar cells is still limited by deep defects, low minority carrier lifetime and high recombination rates at the CZTS/CdS interface. The objective of this study was to find an effective method to reduce interface recombination of CZTS monograin layer solar cells. Two-step heterojunction formation process was applied by controlling the intermixing of Cd and Cu in the CZTS/CdS interface, which resulted in improved device efficiency up to 11.7%. Surface analysis by X-ray photoelectron spectroscopy confirmed the Cd diffusion into surface of CZTS after CdS air-annealing by forming an ultra-thin Cu2ZnxCd1-xSnS4 layer. Also, external quantum efficiency measurements showed that the absorption edge shifts to longer wavelengths with addition of Cd into CZTS surface layer. This surface modification and replacement of CdS:Cu buffer layer by fresh CdS greatly reduced the interface recombination and improved the junction quality, contributing to an enhancement of JSC ∼3 mA/cm2 (from 20.5 to 23.6 mA/cm2), and fill factor ~14% (from 59.4 to 67.7%). Serial resistance of the CZTS monograin layer solar cells was significantly reduced from 2.4 Ω cm2 to 0.67 Ω cm2. To understand in more detail the electrical behavior of highest efficiency CZTS monograin layer solar cell, the temperature dependent current–voltage characteristics were analyzed.