Annealing evolution to MgCl2 treated CdSe absorber layers for solar cells

The CdCl 2 treatment is well-known crucial step to considerably modify the physical properties of absorber layer and power conversion efficiency of associated Cd-based solar cell devices. However, the CdCl 2 is a carcinogenic, water-soluble compound and entails more safety procedures to use as activation agent on absorber and window layers together with associated interface or junction to the device. Present meticulous study focuses on impact of MgCl 2 annealing treatment on physical properties of thermally deposited CdSe films in order to find appropriate alternative to conventionally toxic CdCl 2 treatment. All the films are crystallized in mixture of cubic and hexagonal phases where crystallinity of films is found to improve along with grain growth upon MgCl 2 treatment. Optical energy band gap of treated films lied within range 1.60–1.70 eV and films showed two photoluminescence peaks at ~ 625 nm and ~ 675 nm which are related to deep level defects and near band emission of CdSe system, respectively. Surface topographical analysis showed variation in average surface roughness from 32 nm to 126 nm and grain size from 39 nm to 60 nm with MgCl 2 activation treatment and found maximum for 300 °C activated films. The scrutinized results reveal that CdSe films activated with MgCl 2 at 300 °C could be suitable alternative absorber layer to the Cd-based solar cells.