Quantifying Losses in Open-Circuit Voltage in Solution-Processable Solar Cells

Abstract

The maximum open-circuit voltage of a solar cell can be evaluated in terms of its ability to emit light. We herein verify the reciprocity relation between the electroluminescence spectrum and subband-gap quantum efficiency spectrum for several photovoltaic technologies at different stages of commercial development, including inorganic, organic, and a type of methyl-ammonium lead-halide CH 3 NH 3 PbI 3−x Cl x perovskite solar cells. Based on the detailed balance theory and reciprocity relations between light emission and light absorption, voltage losses at open circuit are quantified and assigned to specific mechanisms, namely, absorption edge broadening and nonradiative recombination. The voltage loss due to nonradiative recombination is low for inorganic solar cells (0.04-0.21 V), while for organic solar cell devices it is larger but surprisingly uniform, with values of 0.34-0.44 V for a range of material combinations. We show that, in CH 3 NH 3 PbI 3−x Cl x perovskite solar cells that exhibit hysteresis, the loss to nonradiative recombination varies substantially with voltage scan conditions. We then show that for different solar cell technologies there is a roughly linear relation between the power conversion efficiency and the voltage loss due to nonradiative recombination.

Study of the Contributions of Donor and Acceptor Photoexcitations to Open Circuit Voltage in Bulk Heterojunction Organic Solar Cells

“…This implies that both the donor and acceptor photoexcitations can contribute to the achievable open circuit voltage as well as the photovoltaic performance of BHJ OSCs; this agrees with our earlier results [45] [68], 0.34-0.44 V for a range of donor-acceptor blends [69], 0.38 V for OC 1 C 10 -PPV:PCBM solar cells [12], and 0.30-0.60 V for BHJ OSCs [20]. Other low voltage offsets ( E DA/q − V j OC ) that have been reported recently are 0.25 V for an evaporated bilayer OSC [70], 0.23 V and 0.26 V for diketopyrrolopyrrole-thieno[2,3-f]benzofuran (DTD):PC 60 BM and DTD:naphthalene diimide acceptor-polymer (N2200) systems, respectively [71], and 0.34-0.40 V for BHJ OSCs [72], with which our calculated values also somewhat agree in the range.…”

Selection Metric for Photovoltaic Materials Screening Based on Detailed-Balance Analysis

“…Numerous other properties such as the mobility [16,17], the absorption coefficient [18,19], the charge-carrier lifetime [18][19][20], and the luminescence quantum efficiency [21][22][23][24][25][26][27] have an enormous effect on a solar cell's performance. Hence, there have been various studies to calculate a more realistic efficiency limit beyond the SQ limit for different technologies and assumptions [18,19,[28][29][30][31][32][33][34][35][36].…”

Origin of Open-Circuit Voltage Loss in Polymer Solar Cells and Perovskite Solar Cells

“…[16][17][18][19] In contrast, the E loss for perovskite solar cells with the architecture, based on either 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 4 dense TiO 2 (d-TiO 2 ) or mesoporous TiO 2 (mp-TiO 2 ) electron-transporting material, is reported to be ≈0.4-0.5 eV. [20][21][22][23] Such values are much larger than the radiative limit (0.25-0.30 eV)…”