In this work, we obtain the highest reported power conversion efficiency (13.3%) for sulfur-free CIGSe solar cells by solution processing. Intentional sodium incorporation is achieved directly by dissolving sodium salts in the ink. The effect on solar cell properties of three sodium sources is investigated: NaCl, NaHCO 2 , and NaSCN. A comparison is made with absorbers grown on soda-lime glass substrates and in the absence of sodium sources. The incorporation via sodium salts yields significantly better results, which is attributed to enhanced-sodium availability. A comparison with identically annealed sputtered metal precursor layers capable of delivering 15.1% module efficiency suggests that the cell results are limited by the selenization procedure.

No abstract

The EQE can be simulated from EQE R taking into account the filtering of photons through ZnSe and the collection losses of charge carriers in the absorber layer underneath ZnSe. To consider the collection losses it is necessary to compute the total volume of absorber layer underneath ZnSe and the fraction of it which is still subject to carrier collection.

A simple and eco-friendly method for solution processing of Cu 2 SnS 3 p-type semiconductor absorbers using a water-based precursor solution is presented. Cu 2 SnS 3 layers were processed by chemical spray pyrolysis deposition of the precursor solution onto Mo-coated glass substrates at 350°C. The as-prepared layers were placed inside a graphite susceptor with S and SnS powders and were annealed in a tube furnace at 550°C. The impact of the annealing step on structural, morphological and device characteristics of the prepared layers was studied. The as-prepared layers were crack-free with fine grains and dominant tetragonal Cu 2 SnS 3 structure. A denser and compact Cu 2 SnS 3 layer with larger grains was formed upon annealing accompanied by a structural phase transition from the tetragonal polymorph to the monoclinic phase. The as-prepared Cu 2 SnS 3 layers showed no photovoltaic activity, whereas the annealed layers showed a device efficiency of 0.65%. A short air annealing of the complete Cu 2 SnS 3 device at 250°C improved the overall device performance and increased the device efficiency to 1.94%. Mechanical removal of shunt paths led to Cu 2 SnS 3 device with 2.28% efficiency.

No abstract