Antimony Selenide Thin Film Solar Cells with an Electron Transport Layer of Alq3*

Abstract

We fabricated Sb2Se3 thin film solar cells using tris(8-hydroxy-quinolinato) aluminum (Alq3) as an electron transport layer by vacuum thermal evaporation. Another small organic molecule of N,N’-bis(naphthalen-1-yl)-N,N’-bis(phenyl)benzidine (NPB) was used as a hole transport layer. We took ITO/NPB/Sb2Se3/Alq3/Al as the device architecture. An open circuit voltage (V oc) of 0.37 V, a short circuit current density (J sc) of 21.2 mA/cm2, and a power conversion efficiency (PCE) of 3.79% were obtained on an optimized device. A maximum external quantum efficiency of 73% was achieved at 600 nm. The J sc, V oc, and PCE were dramatically enhanced after introducing an electron transport layer of Alq3. The results suggest that the interface state density at Sb2Se3/Al interface is decreased by inserting an Alq3 layer, and the charge recombination loss in the device is suppressed. This work provides a new electron transport material for Sb2Se3 thin film solar cells.