Recombination mechanisms in highly efficient thin film Zn(S,O)/Cu(In,Ga)S2 based solar cells

Abstract

Progress in fabricating Cu(In,Ga)S2 based solar cells with Zn(S,O) buffer is presented. An efficiency of 12.9% was achieved. Using spectral response, current-voltage and temperature dependent current-voltage measurements, current transport in this junction was studied and compared to that of a highly efficient CdS/Cu(In,Ga)S2 solar cell with a special focus on recombination mechanisms. Independently of the buffer type and despite the difference in band alignment of the two junctions, interface recombination is found to be the main recombination channel in both cases. This was unexpected since it is generally assumed that a cliff facilitates interface recombination while a spike suppresses it.

Study of Zn(O,S) films grown by aerosol assisted chemical vapour deposition and their application as buffer layers in Cu(In,Ga)(S,Se)2 solar cells

“…Therefore, the amount of In and Cd in the chalcopyrite-based solar cell structures needs to be reduced. Due to their abundance and harmlessness Zn compounds can be potential candidates to be used as buffer layers in solar cell structures (Ennaoui et al, 2003;Kushiya, 2014;Merdes et al, 2009). For the last decade, Zn(O,S) has been used as an effective, non-toxic, cost-efficient buffer layer in solar cell structures uffi re et l nn oui rimm et l ultqvist et l 9 lenk et l l t er-j rkm n et l., 2006; Ramanathan et al, 2012;Sáez-Araoz et al, 2008;Witte et al, 2013).…”

Chalcopyrite compound semiconductors for thin film solar cells

“…The sulfide semiconductor Cu(In,Ga)S 2 covers the ideal band gaps for a top cell in a tandem application with CuIn(Ga)Se 2 or Si [41,42]. The field has been recently renewed by the development of a cell with efficiency above 15% based on higher substrate temperatures [43].…”

Structural regulation of electrochemically deposited copper layers for fabrication of thin film solar cells with a CuInS2 photoabsorber

“…These CuInS 2 and Cu(In,Ga)S 2 thin films have been prepared by various methods, such as coevaporation of elements [3], sequential sputtering of thin layers of elements followed by sulfurization [4], electrodeposition [5] and spraying [6]. Highest conversion efficiencies of CuInS 2 -and Cu(In,Ga)S 2 -based solar cells have been achieved by those prepared from sputterdeposited CuInS 2 and Cu(In,Ga)S 2 thin films [1,2]. However, the use of such vacuum techniques has many disadvantages for a large-area application, such as high equipment costs and significant losses of raw materials.…”

“…Thin film solar cells based on CuInS 2 and that alloyed with gallium (Cu(In,Ga)S 2 ) have reached conversion efficiencies as high as 11.4% [1] and 13.0% [2], respectively. These CuInS 2 and Cu(In,Ga)S 2 thin films have been prepared by various methods, such as coevaporation of elements [3], sequential sputtering of thin layers of elements followed by sulfurization [4], electrodeposition [5] and spraying [6].…”