Thermally-derived liquid phase involving multiphase Cu(In, Ga) Se2 nanoparticles for solution-processed inorganic photovoltaic devices

In the past decade, wet chemical strategies for solution-based Cu(In, Ga) Se-2 (CI(G) Se) photovoltaic devices have gained a tremendous amount of attention in solar-cell research fields. In particular, nanoparticles allowing for liquid-phase densification have been recognized as viable candidates for advancements in photovoltaic devices. In this study, multiphase CIGSe nanoparticles are synthesized by the microwaveassisted solvothermal method, in which the chemically incorporated CuSe2 and Se phases form liquid phases for inducing vigorous reactions at elevated temperatures. The morphological/crystalline structural properties of multiphase nanoparticles are analyzed, in conjunction with the temperature dependent evolution in multiphase nanoparticle-incorporating functional layers. Furthermore, we examine physical parameters including the cell performance, shunt conductance, and series resistance for multiphase CIGSe nanoparticle-derived solar cells, from which the cell performance-limiting factors are discussed.