HZB researchers reach 23.26% record efficiency for tandem perovskite-CIGS solar cell

A team led by Prof. Steve Albrecht from the HZB has announced a new world-record: a tandem solar cell with certified efficiency of 23.26% that combines the semiconducting materials perovskite and CIGS. One reason for this success lies in the cell’s intermediate layer of organic molecules: they self-organize to cover even rough semiconductor surfaces. Two patents have been filed for these layers.

World record for tandem perovskite-CIGS solar cell image

Perovskite-based solar cells have experienced an incredibly rapid increase in efficiency over the last ten years. The combination of perovskites with classical semiconductor materials such as silicon and copper-indium-gallium-selenide (CIGS) compounds in tandem solar cells promises low-cost, high-performance solar modules for the future. However, losses at the electrodes between the two semiconductors considerably reduce the efficiency.

Flexible tandem perovskite/CIGS solar cells with 23% conversion efficiency reported by Solliance and MiaSolé

Solliance and U.S-based MiaSolé announced a new record - power conversion efficiency of 23% on a flexible tandem solar cell: a top flexible semi-transparent perovskite solar cell with a bottom flexible copper indium gallium selenide (CIGS) cell.

Solliance and Miasole's 23%efficiency tandem perovskite/CIGS cells image

This achievement comes only 9 months after the January 2019 announcement by Solliance and MiaSolé regarding a flexible solar cell with an impressive power conversion efficiency of 21.5%. The solar cell, similarly to this newly announced one, combined two thin-film solar cell technologies into a 4 terminal tandem solar cell stack: a top flexible semi-transparent perovskite solar cell with a bottom flexible copper indium gallium selenide (CIGS) cell.

New "Capitano" project aims to develop CIGS-perovskite tandem cells

German university the Karlsruhe Institute of Technology (KIT), the Center for Solar Energy and Hydrogen Research Baden-Würtetemburg (ZSW) and CIGS module manufacturer Nice Solar Energy have announced an ambition to design tandem PV modules based on CIGS and perovskite, which can theoretically achieve efficiencies well above 30%.

The joint ‘Capitano’ project will run for three years and has received more than €5 million from Germany’s Federal Ministry for Economic Affairs and Energy. The aim of the project is to develop cells with stable higher efficiencies, which can be interconnected to form efficient tandem solar modules.

Achieving 26.0% efficient monolithic perovskite silicon tandem solar cells and analyzing the performance as a function of photocurrent mismatch

Researchers from Helmholtz-Zentrum Berlin (HZB), Eindhoven University of Technology and Technical University Berlin have combined rear junction silicon heterojunction bottom cells with p–i–n perovskite top cells into highly efficient monolithic tandem solar cells with a power conversion efficiency (PCE) of 26.0%.

The influence of current mismatch on device performance in tandem perovskite silicon solar cells imageColored cross sectional SEM image of the top cell (upper panel) and back side of the bottom cell (lower panel) of a typical monolithic tandem solar cell used in this work. (b) schematic device layout of the tandem architecture utilized in this work.

Starting from a certified efficiency of 25.0%, further improvements have been reached by reducing the current mismatch of the certified device. The top contact and perovskite thickness optimization allowed increasing the JSC above 19.5 mA cm−2, enabling a remarkable tandem PCE of 26.0%, however with a slightly limited fill factor (FF).

University of Toronto researchers create a more stable electron selective layer for PSCs and tandem solar cells

Researchers at the University of Toronto have designed a method of growing a more stable electron selective layer for perovskite solar cells and tandem solar cells combining crystalline silicon with perovskite.

University of Toronto researchers make Quantum Dots and Perovskite Solar Cells at 150°C image

Perovskite raw materials can be mixed into a liquid in a kind of ‘solar ink.’ This solar ink could be printed onto glass, plastic or other materials with a relatively simple inkjet printing process. However, in order to generate electricity, electrons excited by solar energy from perovskite cells must be extracted from a layer of quantum dots that is held together by a passivation layer. Some types of quantum dots are known to change their 3D structure even at room temperature, making them transparent and ineffective. This passivation layer is also known to break down at temperatures above 100°C. The team’s breakthrough made both quantum dots and perovskites more stable when combined than they are separated and the solar cell combining of Perovskite material and quantum dots achieved 20.1% efficiency.