Periodic Reporting for period 1 - SUSNASOL (Designing of Environmentally Friendly Colloidal Nanocrystals for Sustainable Solar Cell Manufacturing)
Período documentado: 2020-07-01 hasta 2022-06-30
Rapid climate change and severe energy crisis has driven the development of high-efficiency, low-cost photovoltaic technologies. This stimulates the evolution of photovoltaic (PV) technologies from crystalline silicon (first generation) to thin film PV (second generation) with promises in further lowered cost and new building integrated applications (BIPV). However, limited by the available thin film PV technologies at the current stage, this ambition cannot be realized without relying on toxic or scarce materials (e.g. Cd, In, Ga, Pb, etc.). To meet the requirement of sustainability in power generation, kesterite or Cu2ZnSnS4 has become an attractive PV material due to its superior optical property and earth-abundant, environment-friendly composition that can meet the terawatt scale needs from the solar energy market for the next decade. But the high density of defects (i.e. Cu-Zn antisites), chemically unstable interface (Kesterite/Mo glass), toxic Cd in standard buffer layer, results in its solar cell efficiency loss and hindering the non-toxic advantage of the active layer. Therefore, SUSNASOL aims at the development of environmentally friendly solar cell technologies, more specifically, applying Ag incorporated kesterite with optimized device configuration to tackle the long remaining issues raised by material defects and interfaces, so as to build the new platform of low-temperature manufacturing towards high-efficiency, sustainable PV cells.
SUSNASOL investigated Ag-incorporated kesterite with post processing and fine tuning to have developed research line on fully environmentally friendly (Cd-free), highly efficient photovoltaic cells based on an innovative superstrate device configuration and ultrathin absorber (about 10 times thinner than standard thin film solar cells). More specifically, during the project, multiple fabrication routes have been comparatively studied and optimized, advanced characterizations on material, optical, electrical properties have been conducted, in-depth device testing have been performed to probe the carrier transport dynamics and provide feedback to optimization (assisted by theoretical modelling). At the end of the project, via low-cost solution processing, SUSNASOL has approached the targeted 10% power conversion efficiency in an ultrathin, superstrate kesterite solar cell, which is the highest among all reported devices of this type, and also lead this long-overlooked research direction to a technological competitive level. The results have been published on/submitted to high-quality, peer-review journals with open-access, also presented at international schools and conferences attracting attention from the community in environmentally friendly photovoltaic research; newly published results has been shared via internet platforms (e.g. ResearchGate, and Linkedin etc.).
SUSNASOL developed the strategy of applying Ag to tune the energy levels of kesterite so as to enable the match between TiO2 as a novel buffer material that is free of any toxic elements, further, by developing advantageous superstrate device structure, ultrathin absorber, and an innovative compositional refining step, a device with record high efficiency (9.7%) has been developed at the end of the project as an important progress beyond the state-of-the-art (which was only 5%). This progress will boost the development of this particular research direction and draw attention from the research community, further elevated efficiency will certainly create industrial/business opportunities. Moreover, the results from the project have provided innovative solutions to the current challenges in environmentally friendly thin film photovoltaics, which is of importance as valid measures to sustainably address the severe issues of climate change and energy crisis.