The use of transparent conducting oxides (TCO) as a back contact for Cu 2 ZnSn(S,Se) 4 (CZTSSe) thin film solar cell enables light absorption from both front and rear sides and allows for the fabrication of semi-transparent photovoltaic devices. However, the CZTSSe solar cell based on TCO substrate suffers from high parasitic losses owing to the long post-annealing time at elevated temperature required for high-quality absorber. This work aims to overcome this issue by carefully tailoring the annealing conditions to obtain high-performance solar cell. Rapid thermal processing is used to instantaneously generate high Se vapor pressure at target temperature and shorten the annealing time. The crystalline quality, morphology, and particularly the photovoltaic performance of the resulting CZTSSe thin film are systematically investigated. It is found that the increase of annealing temperature and time improves the crystalline quality but unfortunately deteriorates the device performance owing to increasing parasitic losses. Increasing the amount of Se allows to get highly crystalline absorber within 7 min of annealing, yielding a total area 5.56% efficient CZTSSe solar cell with front illumination resulting from reducing parasitic losses. This work provides a simple approach to preserve the back contact without using a complex interfacial layer.
Hong Liu,Liyang Yu,Haoyong Jin,He Xia,xiaoxiong wang,liang wang,dezheng Li,jiangli Zhao,Jichuan Qiu,Yuanhua Sang,ning yang,Ning Lu
The repair of traumatic spinal cord injury (SCI) remains a challenge due to the non-regenerative nature of functional neurons in adults. Neural stem cell (NSC)-based therapy has emerged as a promising approach for the treatment of SCI by replacing the damaged neurons with differentiated stem cells. However, directing the neuronal differentiation of implanted stem cells in the injury microenvironment is of great difficulty, especially considering that SCI is generally associated with severe fibrotic tissue infiltration, neuron inflammation, and tissue adhesion. Here, we propose a dual functional Janus film capable of preventing tissue adhesion and promoting the neuronal differentiation of stem cells for the treatment of SCI. The Janus film is composed of a layer of polylactic acid (PLA) and a layer of chitosan (CS) grafted with IKVAV peptides. The PLA layer prevents the invasion of the fibrotic tissue, while the IKVAV peptide-grafted CS layer offers support for NSC implantation and thus the neuronal differentiation of the NSCs. When serving as the dura patch, the Janus films seeded with NSCs promote the recovery of motor function and the regeneration of the injured spinal cord tissue of SCI rats. This dual functional Janus film holds great promise for treating SCI in combination with stem cell therapy.
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