Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener Bulk heterojunction polymer solar cell and perovskite solar cell: Concepts, materials, current status, and opto-electronic properties Farzaneh Arabpour Roghabadi a , Najmeh Ahmadi b , Vahid Ahmadi a, ⁎ , Aldo Di Carlo c , Karim Oniy Aghmiuni b , Ali Shokrolahzadeh Tehrani a , Farzaneh Sadat Ghoreishi b , Masoud Payandeh a , Nasibeh Mansour Rezaei Fumani d a Faculty of Electrical and Computer Engineering, Tarbiat Modares University, P.O. Box: 14115-196, Tehran, Iran b Department of Nanoelectronic, Tarbiat Modares University, Tehran, Iran c C.H.O.S.E. – Center for Hybrid and Organic Solar Energy, Department of Electronics Engineering, University of Rome Tor Vergata, Rome, Italy d Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran ARTICLE INFO Keywords: Bulk heterojunction polymer solar cell Perovskite solar cell Optical properties Electrical properties Configuration Mechanism ABSTRACT Recently, the demand for sustainable and clean energy resources has led to an intense growth in the development of different types of solar cells. Among all types of photovoltaics, polymer solar cells and perovskite solar cells have received extensive attention because of their potential for achieving cheap, light weight, facile and fast fabricated devices. Bulk heterojunction polymer solar cells have been considered for about two decades, while perovskite ones have introduced just for 7 years. Comparison of these devices indicates a higher performance for perovskite solar cells. This review starts by comparative introducing of configurations, materials, mechanisms, fabrication methods, crystalline natures, band gap tuning, and the current status of the photovoltaic perfor- mances of polymer and perovskite solar cells. We emphasize the importance of the optoelectronic properties of the absorber layers including absorption coefficient, exciton binding energy, exciton dissociation, exciton and charge carrier lifetimes, charge carrier mobility, and exciton and charge diffusion lengths. Suggestions regarding needed improvements and future research directions in the field of polymer and perovskite solar cells are provided. 1. Introduction In recent years, the demand for sustainable and clean energy re- sources has led to an intense growth in the development of solar cells that directly convert sun light into electricity. Solar cell is one of the most promising technologies for harvesting the sun energy as the lar- gest noncarbon- based natural source. Photovoltaic technology should meet three factors of efficiency, stability, and low cost to reach the industrial demonstration (Krebs, 2008). Silicon photovoltaics as the first generation solar cells are stable, with long lifetime around 25 years and power conversion efficiencies (PCE) as high as 20%, but their fabrication processes are too complex and expensive (Krebs, 2008). Photovoltaic uptake has been growing to introduce sufficient alter- natives to the conventional solar cells. The lowest cost and simplest fabrication method for solar cells is solution processing that provides roll-to-roll printing as a beneficial method for large scale production. Some of the most promising technologies utilized for decreasing the manufacturing costs of solar cells are based on solution process, including dye-sensitized solar cells (DSSCs) (Ghadiri et al., 2010), QD- sensitized solar cells (QD-SSCs) (Ghoreishi et al., 2014), small molecule organic or polymer solar cells (Arabpour Roghabadi et al., 2016a, 2016b, 2016c; Ghasemi Varnamkhasti et al., 2012; Tavakkoli et al., 2011), and perovskite solar cells (PSCs) (Arabpour Roghabadi et al., 2016a, 2016b, 2016c). Among all types of photovoltaics, bulk hetero- junction polymer solar cells (BHPSCs) and PSCs have received extensive attentions because of their potentials for achieving cheap, facile and fast fabricated, and light weight solar cells. BHPSCs have been con- sidered for about two decades, while PSCs have introduced just for 7 years. Comparison of these two types of photovoltaics shows a higher performance for PSCs. In this review, first, a history of both devices is reported and their configurations and mechanisms are introduced. The common applicable materials for their layers are presented and com- pared. In addition, the opto-electronic properties of their absorber layers are reviewed and compared. There are several points that should be mentioned: https://doi.org/10.1016/j.solener.2018.07.058 Received 12 May 2018; Received in revised form 19 July 2018; Accepted 21 July 2018 ⁎ Corresponding author. E-mail address: v_ahmadi@modares.ac.ir (V. Ahmadi). Solar Energy 173 (2018) 407–424 0038-092X/ © 2018 Elsevier Ltd. All rights reserved. T