Effect of Bathocuproine Concentration on the Photovoltaic Performance of NiOx-Based Perovskite Solar Cells

Abstract

Abstract. Bathocuproine (BCP) (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) is a well-known material that is employed as a hole-blocking layer between electron transport layer (ETL) and metal electrode in perovskite solar cells. It has been demonstrated that the use of BCP as a buffer layer between the ETL and the metal electrode in perovskite solar cells is highly beneficial. In literature, BCP is coated using vacuum processing techniques. Vacuum processing techniques require more energy and cost-effective processing conditions. In this work, we used BCP layers processed through wet processing techniques using sol-gel method with different concentrations. We achieved a short circuit current density (Jsc) of 16.1 mA/cm2 and an open circuit voltage (Voc) of 875 mV were acquired and a fill factor (FF) of 0.37 was calculated for perovskite solar cells without a BCP layer leading to a power conversion efficiency (PCE) of 5.32 % whereas Jsc of 19 mA/cm2, Voc of 990 mV were achieved and a FF of 0.5 was calculated for perovskite solar cells employing BCP layers with concentration of 0.5 mg/ml and spin cast at 4000 rpm, leading to a PCE of 9.4 %. It has been observed that the use of a BCP layer with an optimized concentration led to an improved device performance with an increase of 77 % in PCE in ambient air under high humidity conditions for planar structure perovskite solar cells in the configuration of ITO/NiOx/MAPbI3/PCBM/BCP/Ag. 
 Resumen. Batocuproina (BCP) (2,9-dimetil-4,7-difenil-1,10-fenantrolina) es un material que se emplea como capa de bloqueo de huecos entre la capa transportadora de electrones (ETL) y el electrodo metálico en celdas solares basados en perovskitas. Se ha demostrado que el uso de BCP como capa amortiguadora entre el ETL y el electrodo metálico en las celdas solares de perovskita es beneficioso. Comúnmente el BCP se recubre mediante técnicas de procesamiento al vacío, las cuales requieren altos costos energéticos. En este trabajo utilizamos capas de BCP procesadas mediante técnicas de procesamiento húmedo utilizando el método sol-gel. Logramos una densidad de corriente de cortocircuito (Jsc) de 16.1 mA / cm2 y un voltaje de circuito abierto (Voc) de 875 mV y se calculó un factor de llenado (FF) de 0.37 para las celdas solares de perovskita sin una capa de BCP lo que conduce a una eficiencia de conversión de energía (PCE) de 5.32%. Para celdas solares de perovskita que emplean capas de BCP con concentración de 0.5 mg/ml y centrifugado a 4000 rpm el valor de Jsc fue de 19 mA / cm2, se lograron Voc de 990 mV y se calculó un FF de 0.5, lo que lleva a un PCE del 9,4%. Se observó que el uso de una capa de BCP con concentración optimizada puede conducir a un rendimiento mejorado del dispositivo con un aumento del 77% en PCE en el aire ambiente, en condiciones de alta humedad, para celdas solares de perovskita de estructura plana en la configuración de ITO / NiOx / MAPbI3 / PCBM / BCP / Ag.

Vacuum‐Processed Perovskite Solar Cells: Materials and Methods

“…TCO/HTL/perovskite/C 60 /BCP/Ag(Au) is generally used in the p–i–n structure, and bathocuproine (BCP) is used as a hole‐blocking layer between C 60 and the metal electrode ( Figure a). [ 53 ] To be used as an ETL in a p–i–n structure, the perovskite layer must be well covered. However, Figure 8d illustrates the presence of defects such as pinholes on the surface after the deposition of C 60 on the perovskite layer.…”