Deep defects in Cu2ZnSnS4 monograin solar cells

In this report Cu2ZnSnS4 (CZTS) monograin layer (MGL) solar cells were studied using admittance spectroscopy (AS) (frequency range 20Hz-10 MHz) and temperature dependence of quantum efficiency (QE) curves (T=10K-300K). These studies revealed two deep defect states at EA1= 120 meV and at EA2= 167 meV. The first state was present in different CZTS cells while the second state had somewhat different properties in different cells. The temperature dependence of QE curves showed a shift of the long wavelength edge with increasing temperature by about 110 meV towards higher energy. The possible origin of the observed deep defect states is discussed.