To achieve the global objectives for CO2-emission reductions, it is essential to implement the use of green energy. This can be achieved by developing new renewable energy technologies such as photovoltaics to harvest sunlight. Organic solar cells (OSCs) can be used to produce semitransparent photovoltaic windows with low-cost solution processes such as spin-coating. However, OSCs have the following major issues that need to be overcome to ensure that they can be manufactured in a safe, sustainable and economical manner: 

(1) Strongly light absorbing materials require the use of multistep advanced chemical synthesis which generates a large amount of hazardous organic solvent and byproduct wastes. 

(2) During active layer deposition by spin-coating, 90% of the active material and hazardous solvents are wasted and released in the environment. 

(3) The methods employed for device fabrication require high initial investments and running costs and thus cannot be easily implemented in developing or least developed countries. 

To overcome these issues, we propose several solutions to either decrease the cost or the environmental impact of OSC-based semitransparent photovoltaic window manufacturing. 

The first solution consists in employing three active materials with complementary absorption properties to harvest the same amount of light as broadly absorbing materials that require more advanced chemistry. We also study the effect of replacing synthetic organic semiconductors with natural ones such as carotenoids that can be extracted directly from tomatoes or carrots. Finally, we introduce a new process called push-coating that yields similar performances as spin-coating but employs 20 times less hazardous solvents than spin-coating and generates no material wastes. For each of the solutions presented above, we studied the nanomorphology of the resulting OSCs and correlated them with the device performances. Our results clearly indicate that OSCs show great promise for low carbon footprint photovoltaic solutions to overcome global warming issues as long as green & sustainable fabrication methods are employed.